Visual Space Orientation and the Onset Repulsion Effect: The Role of Visual Gravitational Motion in Modulating Spatial Mislocalizations

Visual Space Orientation and the Onset Repulsion Effect: The Role of Visual Gravitational Motion in Modulating Spatial Mislocalizations | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Visual Space Orientation and the Onset Repulsion Effect: The Role of Visual Gravitational Motion in Modulating Spatial Mislocalizations Rodrigo Ribeiro Freitas, Samuel Silva, Nuno Alexandre De Sá Teixeira This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8662288/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract The perceived onset position of a moving target has been found to be systematically displaced backwards, in a direction opposite to motion direction, a phenomenon coined as the Onset Repulsion Effect (ORE). Of particular relevance to the present work, the ORE has been found to be increased for ascending, in comparison with descending targets, a pattern putatively due to the greater effort required to launch an object upwards against gravitational acceleration. Although this account remains speculative, it raises the possibility that the effect may reflect a ‘natural history’ to dynamic events, akin to the windup which precedes throwing an object, resulting in a backward overcompensation of the target’s onset location. To further explore the role played by visual gravitational motion on the ORE, two experiments were conducted in which participants were required to indicate the onset location of targets moving along one out of sixteen possible trajectories. Differences between the actual and the perceived motion onset were measured and subjected to a discrete Fourier decomposition. Results disclosed an enhanced ORE for targets moving upwards (Gravity Related Component; Experiment 1), an effect that increased with longer retention intervals. Experiment 2 further demonstrated that the Gravity Related Component is tilted in congruence with the orientation of a visual background context. These findings are discussed within the framework of internal models of gravity, human spatial orientation, and their influence on visual motion perception. Psychology Cognitive Neuroscience Onset Repulsion Effect Motion Perception Spatial Orientation Vertical Anisotropy Isotropic Component Gravity Related Component Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Gravity as a reference for human perception and action If you toss a handful of confetti into the air at a birthday celebration, you will immediately notice that each piece inevitably falls back to the ground. This simple observation illustrates the omnipresent influence of gravity, a fundamental physical force that attracts masses toward the Earth’s centre (Volkmann & Baluška, 2006 ). Beyond its physical definition, gravity provides the primary reference for orientation, balance, and movement in all terrestrial organisms (Vinogradova et al., 2021 ). Within the animal kingdom, humans have evolved a bipedal, upright posture. This vertical orientation offers numerous adaptive benefits, such as freeing our hands for object manipulation, elevating our line of sight, and enabling metabolically efficient locomotion (Alexander, 2004 ; Crevecoeur et al., 2014 ). Although our ability to maintain a vertical posture confers several advantages, it also renders us less stable compared to quadrupedal locomotion, thereby increasing susceptibility to imbalance and falls. Consequently, the ability to accurately estimate our orientation relative to gravity is essential for maintaining posture and ensuring safe locomotion (Dakin & Rosenberg, 2018 ). In addition to its biomechanical importance, gravity profoundly shapes sensorimotor and perceptual processes. Empirical evidence shows that internal representations of gravity play a role in sensorimotor tasks, including catching (de la Malla & López-Moliner, 2015 ; Tresilian, 1993 ), motor control (Bock et al., 1992 ; Gaveau et al., 2011 ), spatial perception (Clément et al., 2008 , 2013 ), and even for the perception of motion patterns (Maffei et al., 2015 ; Westhoff & Troje, 2007 ). Given that the entirety of human evolution and individual development has taken place under the influence of Earth’s gravity, the human perceptual system has become finely attuned to this ubiquitous force. Perception of gravity arises from the coordinate contribution of multisensory modalities—vision, the vestibular system (comprising the otolith organs and semicircular canals), proprioception (receptors in muscles and tendons), and other somatic cues originating from internal organs such as the kidneys and intestines (Jörges & López-Moliner, 2017 ). Although vestibular and proprioceptive cues provide direct information about body orientation and acceleration, vision plays a crucial role in the perception of gravity by offering contextual and referential visual cues that help define the subjective sense of verticality. Visual information contributes to the establishment of visual reference frames, such as the orientation of the surrounding environment—strongly influenced by the presence of a horizon—which can modulate offset spatial mislocalizations (De Sá Teixeira et al., 2024 ; Freitas et al., 2025 ; Freitas & De Sá Teixeira, 2021 ). Beyond static orientation cues, vision supplies dynamic information, enabling the visual system to infer acceleration consistent with gravitational motion. Systematic spatial mislocalizations shaped by gravity These lines of reasoning converge in the domain of motion perception, which, according to psychophysical research on spatial mislocalization phenomena involving moving stimuli, is not entirely reliable. Accurately perceiving and predicting motion is crucial for effective interaction with a dynamic world. Everyday actions, such as intersecting a moving object, driving in traffic, or crossing a busy street, depend on the visual system’s ability to anticipate the future state of moving stimuli (Hogendoorn, 2020 ; Nijhawan, 1994 , 2002 , 2008 ). Far from functioning as a passive receiver of sensory input, the human perceptual system actively constructs predictive representations of motion to compensate for delays incurred during the transmission and cortical processing of visual information, which amount to approximately 70 ms (Lamme & Roelfsema, 2000 ). Without such predictive mechanisms, this neural lag would substantially impair our ability to perceive and respond adaptively in a continuously changing environment. Even under simple laboratory conditions, such as viewing a single dot moving across a blank screen, observers systematically misjudge the onset and offset locations of motion. When participants are asked to indicate the offset position of a moving target, they tend to displace it forward, in the direction of motion—Representational Momentum (Freyd & Finke, 1984 ; Hubbard, 1995 ), and downward, in the direction of gravity—Representational Gravity (Hubbard, 1990 , 1998 ; Hubbard & Bharucha, 1988 ). Representational Gravity and Representational Momentum operate along separate axes for horizontally moving targets but converge along the same axis for vertically moving ones. Consequently, motion extrapolation for vertical motion differs depending on direction, being larger for descending and smaller for ascending targets (De Sá Teixeira, 2016 ). Research on Representational Gravity has explored the potential modulation of this effect by several factors, including target characteristics, display configuration, contextual information, and observer-related variables (Hubbard, 2020 ). The existence of Representational Gravity is consistent with the hypothesis that neural systems have evolved to exploit invariant physical regularities, such as the constant acceleration due to gravity, through internal models of gravity that optimize perception and action (Lacquaniti et al., 2013 , 2015 ; McIntyre et al., 2001 ; Zago & Lacquaniti, 2005 ). From forward to backward mislocalizations One of the earliest reported onset mislocalizations is the Fröhlich Effect (Fröhlich, 1923 ), in which a moving target is perceived to start ahead of its actual onset position, displaced forward along the direction of motion (Kirschfeld & Kammer, 1999 ; Müsseler & Aschersleben, 1998 ; Müsseler & Neumann, 1992 ). This effect has been attributed to attentional delays in detecting motion onset (Kerzel & Müsseler, 2002 ; Müsseler & Aschersleben, 1998 ) and to anticipatory or extrapolative mechanisms that bridge perceptual delays (Nijhawan, 1994 ; Whitney & Cavanagh, 2000 ). Interestingly, when the target velocity is reduced, the direction of mislocalization reverses. Under these slower motion conditions (< 15º /second), observers tend to perceive the onset position behind the true starting point—a phenomenon known as the Onset Repulsion Effect (ORE). This phenomenon manifests a displacement opposite to the direction of motion, in a position that was never physically occupied (Thornton, 2002 ). The ORE was initially identified through studies on memory for dynamic events. In a series of experiments conducted by (Thornton, 1999 ), participants observed a dot moving along a complex path with varying directions and speeds. They were then instructed to use a simple interface to reconstruct the observed event as accurately as possible, mapping out the spatial trajectory and assigning appropriate velocities to each segment. Although the primary objective was to examine how memory for dynamic events changes over time, the most significant and systematic error observed was the tendency to place the initial onset point too early along the trajectory of the event. This pattern of error is consistent with findings from Actis Grosso et al. ( 1996 ), who reported similar mislocalizations when observers tracked a dot moving along various curved and straight paths. Empirical evidence demonstrates that the ORE is more pronounced for upward than for downward motions (Thornton, 2002 ). The magnitude of the ORE decreases with the velocity of the moving object (Kerzel & Gegenfurtner, 2004 ), being observed with velocities ranging from 1.96 to 15º/s (Actis-Grosso & Stucchi, 2003 ). Additionally, the effect is confirmed regardless of whether the object is tracked with eye movements or not, and its magnitude is more pronounced when both the onset and offset points of the motion must be remembered (Thornton, 2002 ). In related experiments, Hubbard & Ruppel ( 2011 ) explored the impact of cuing on the ORE with implied motions, finding that mislocalization diminished or even disappeared with the presence of a cue (Müsseler & Tiggelbeck, 2013 ). Further research indicates that this effect is more likely to occur when the target appears on a blank background (Hubbard & Motes, 2002 ), is further from a boundary (Hubbard & Motes, 2005 ), or when the observer's response involves pointing (Kerzel, 2002 ). A key point for motivating this manuscript is that a comprehensive account for the ORE remains elusive. Thornton ( 2002 ) proposed several explanatory mechanisms, including misremembering, misperception, and overcompensation. The misremembering hypothesis posits that the onset position is initially encoded accurately but becomes distorted during the retention interval between observation and report, resulting in a memory-based backward mislocalization. The misperception account suggests that observers respond to a perceptual trace that does not precisely correspond to the true onset of motion. Finally, the overcompensation hypothesis proposes that, when uncertain about the exact onset, observers choose a point further back as a correction, potentially due to real-world expectations that objects do not appear instantaneously without any prior indication. This leads observers to attribute some sort of natural history to the dynamic visual event, akin to the preparatory motion before throwing an object, causing an overcompensation of the target’s starting point. Notably, this overcompensation perspective parallels the medieval impetus theory described by McCloskey ( 1983 ), which itself echoes elements of Aristotelian physics (see Byrne, 2018 ), positing that motion must have a cause. Unlike Newtonian mechanics, where continuous motion requires no sustaining force, the impetus theory posits that a moving object retains an internal force, termed impetus, acquired at launch and gradually depleted over time until natural forces, such as gravity, dominate. This framework resolved a key limitation in Aristotelian physics by providing an explanation for projectile motion without invoking an external sustaining agent. For instance, a classic example demonstrated by Paulus Puchner (1577) illustrated that a cannonball moves in a straight path due to the impetus imparted by the cannon, and when this impetus is exhausted, gravitational forces cause it to fall (cf. Road Runner Physics in Gentner, 2001 ; see also Hecht, 2001 ; Hecht & Bertamini, 2000 ). This analogy underlines the notion that an effort is required both to initiate and maintain motion, an intuition that may underlie perceptual overcompensation in dynamic visual events. The Present Study The present study aimed to investigate whether the perception of motion onset is systematically biased by the direction of motion in the absence of visual contextual cues, and whether such biases reflect an internalized representation of gravity acting on moving stimuli. Building on evidence that when judging the offset position of a moving target, downward mislocalizations (Representational Gravity) arise from predictive internal models of motion, and that backward displacements such as the ORE may stem from compensatory intuitions about object dynamics, we examined onset localization across multiple motion directions and temporal delays. Participants performed a spatial localization task referring to the onset position of a target moving along several possible directions against a blank uniform visual context devoid of visual cues and after an interval of 0, 300, 600, or 900 ms. By evaluating directional asymmetries and temporal dynamics in onset mislocalization, the present study aims to clarify the mechanisms underlying the ORE and to assess whether internal models of gravity shape localization even when no explicit visual gravitational cues are available. Experiment 1 Method Participants. Assuming an effect size of η² p = 0.15, with power set to 0.95 (with α = 0.05), an a priori power analysis, performed with the software G*Power3.1.9.4 , revealed that 6 participants would be required to detect relevant effects with a factorial design given by 16 (target’s trajectory) × 4 (stimulus-cursor asynchrony/retention interval: 0, 300, 600, or 900ms). To strengthen the robustness of statistical inference, thirty-two participants (9 males and 23 females), with ages ranged from 18 to 51 years old ( M = 23.63; SD = 7.88), volunteered for the Experiment. Volunteers attending Psychology courses at the University of Aveiro received partial course credits, while non-student participants were compensated with a 5€ voucher. All participants were unaware of the Experiment’s purpose and had normal or corrected-to-normal vision, with no known vestibular deficits or history of neurologic disorders. The Experiment was preapproved by the ethics committee of the University of Aveiro (Protocol 05-CE/2025). Stimuli. A spatial localization task was conducted within a visual context comprising a uniformly black screen devoid of any visual orientation cues. This black background was chosen, aiming to ensure neutrality and to remove any visual context that could introduce potential biases in the assessment of the ORE. It was done with the purpose of exploring the ORE in its most natural state, making it possible to verify if any tendency would be verified regarding its direction. The selected background was resized to fit the screen’s vertical height (1024 pixels) and standardized to a full-screen window aspect (1280 × 1024 pixels). The task involved a white circle target, with a diameter of 21 pixels (equivalent to about 0.71º of visual angle). Apparatus, Procedure, and Design. Upon arrival at the laboratory, all participants received detailed explanations regarding the experimental protocols. Following this, they were requested to read and sign an informed consent before the experiment's start. Participants sat in an adjustable office chair, positioned in front of a computer screen (with a refresh rate of 60 Hz, a resolution of 1,280 x 1,024 pixels, and a physical size of 37.5 x 30 cm). The screen was adjusted such that the participant’s cyclopean eye was aligned with its centre and at a distance of 50 cm. While participants’ eye movements were not constrained, their visual field was confined to a central circular aperture with the aid of a custom-made blackboard cylinder. Its diameter matching the height of the monitor (30 cm), ensured that participants positioned their heads within it, thereby occluding their peripheral vision (see Fig. 1, panel A). To minimize potential distractions from ambient noise within the laboratory or building, participants wore noise-cancelling earmuffs during the experimental task. A brief break of several minutes was allowed once half of the task was completed. The experimental task was handled and displayed in Python using PsychoPy (Peirce, 2007 , 2008 ) and run on a personal computer. Each trial started with the presentation of a white fixation cross (26 pixels × 26 pixels, about 0.87º × 0.87º) located at the centre of the screen (1 second), subsequently replaced by a moving target represented by a white circle. The target’s starting location was randomly determined within a designated area of 410 x 410 pixels (about 13.78º × 13.78º) and proceeded to move towards the periphery of the visible circular aperture at a speed of 256 pixels per second (about 8.54º/s). The target’s initial position was chosen to ensure an adequate distance from the screen boundaries, thus minimizing potential interference with participants’ judgments of the target’s onset location (cf. Hubbard & Motes, 2005 ). Target’s motion lasted for 1 second, with its trajectory varying randomly across trials between 0º (rightward motion), 22.5°, 45°, 67.5°, 90° (upward motion), 112.5°, 135°, 157.5°, 180° (leftward motion), 202.5°, 225°, 247.5°, 270° (downward motion), 292.5°, 315°, or 337.5°. After covering a total distance of about 256 pixels, the target suddenly vanished. A white circular cursor (diameter of 5 pixels; about 0.17º) appeared on the centre of the screen 0, 300, 600, or 900 ms after the target’s offset. The cursor location onscreen was controllable with a trackball, and the participants were instructed, at the beginning of the experiment, to adjust the cursor’s position to align precisely with the location where the target appeared, referring to its geometric centre. The judged onset location was confirmed by pressing either the left or right button on the trackball (see Fig. 1, panel B). The experiment followed a repeated measures design given by 16 (target’s trajectory) x 4 (stimulus-cursor asynchrony/retention interval: 0, 300, 600, or 900ms), with each condition replicated 12 times, completing a total of 768 trials per participant. Prior to the experiment start, participants could practice the task for a few trials to ensure they understood the task and could operate the trackball. After the experiment concluded, participants took part in a debriefing session where they could make any comment about the experiment and ask any question about the study. Overall, the entire experiment lasted approximately 75 minutes. Figure 1 Laboratorial Setting for the Experiments (Panel A) and Trials Structure for the Spatial Localization Task (Panel B). Note Notice that stimuli sizes are not to scale. Calculations, Hypotheses and Statistical Analyses. On each trial of the experiment, the horizontal and vertical differences of M-displacement were calculated. M-displacement was measured by calculating the deviation in pixels between the participant’s response and the actual onset position measured along the target’s motion axis, such that these values were used to compute the orthogonal projection of the participant’s response along the target’s trajectory. Positive numbers reflect a displacement forward (Fröhlich Effect), while negative values a backward displacement (ORE), relative to motion direction. The individual sets of M-displacements, for each experimental condition and with orientation of target’s trajectory as parameter ( θ ), were subjected to a discrete Fourier decomposition procedure (for a comprehensive elucidation of this procedure, see Sekuler & Armstrong, 1978 ; for an example of this procedure on offset mislocalizations, see also (De Sá Teixeira, 2014 ; De Sá Teixeira et al., 2024 ; Freitas et al., 2025 ; Freitas & De Sá Teixeira, 2021 ). For each set of M-displacements, the Fourier decomposition provides individual estimates of a constant c and harmonic coefficients a i (cosine) and b i (sine) up to i = 4, in accordance with: $$\:{M}_{\theta\:}=c+{\sum\:}_{i=i}^{n}\left({a}_{i}\text{cos}i\frac{\theta\:}{2\pi\:}+{b}_{i}\text{sin}i\frac{\theta\:}{2\pi\:}\right)\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\left(1\right)$$ Note Rightward plots depict the underlying harmonic terms, both algebraically and graphically in polar plots. Given the hypothesis of the existence of ORE, in Eq. 1, the constant c denotes the amount of ORE observed across all motion directions (see Fig. 2 , rightward top plot). The coefficients a 1 and b 1 , when considered jointly, reflect an increased displacement towards one preferred direction (see Fig. 2 , rightward bottom plot). Previous research has revealed an increased backward displacement for ascending targets, compared to descending targets (Thornton, 2002 ), putatively due to the greater effort required to launch an object upwards against the gravitational acceleration. Based on these findings, this experiment aims to understand which parameters significantly contribute to the ORE when performing an onset spatial localization task and how these parameters are affected by the target’s trajectory. In addition, in Experiment 1, an additional goal is to study the evolution of memory for the ORE over time. To statistically evaluate the data obtained on this experiment, the estimated individual values of c , harmonic coefficients a 1 - a 4 , and b 1 - b 4 were obtained from the localization responses for each experiment. These values were then subjected to a mixed multivariate analysis of variance (MANOVA), with retention time (0, 300, 600, or 900 ms) being taken as the repeated-measure factor. In cases where the sphericity assumption was violated, adjustments to the degrees of freedom were made using the Greenhouse-Geisser correction. Results Figure 3, plot A, illustrates the polar plot for the mean ORE as a function of the target’s motion direction (radial lines) and the retention interval (line parameters) for the absence of visual context. Before proceeding with the main analyses, mean ORE for each target’s motion direction and retention intervals were subjected to a one-sample t-test to confirm the presence of backward perceptual displacements. These preliminary analyses revealed that within the absence of visual context, the ORE could be well described by two significant parameters (see Fig. 3, plot A). Specifically, a significant constant c ( p < .001 for all retention intervals), indicates a backward displacement for all directions—which we coin the Isotropic Component (see Fig. 3, plot B). Additionally, a significant b 1 coefficient ( p < .001 for all retention intervals), accounts for a more pronounced backward displacement for ascending targets—which we coin the Gravity Related Component (see Fig. 3, plot B). Figure 3 Schematic Representation of Polar plots depicting the found ORE Note Panel A: Polar plot depicting the found ORE (data markers) and the Fourier-based theoretical adjustments (lines) found for each motion direction and retention times; Panel B: Polar plot of the mean estimated parameter c (Isotropic Component); Panel C: Polar plot of the mean estimated coefficients a 1 and b 1 (Gravity Related Component). To investigate the impact of retention time on the ORE, the estimated individual coefficients ( c , a 1 - a 4 , and b 1 - b 4 ) of Eq. 1 were subjected to a repeated measure MANOVA with retention interval as the within-subject factor. Retention time was found to significantly modulate the b 1 parameter, F (2.513, 77.907) = 3.625, p = .022, partial η² = 0.105, with a significant linear contrast, F (1, 31) = 8.712, p = .006, partial η² = 0.219. Across retention interval conditions, the component b 1 demonstrated a progressive increment, reaching its peak at 900 ms ( M= -14.25; SD = 13.59) (see Fig. 4). No other harmonic terms were found to be significantly affected by the retention time. Figure 4 Mean c parameters (solid black squares and full lines) and b 1 coefficients (open triangles with dashed lines) found for each retention interval (abscissas) Note The vertical bars depict the standard errors of the means. Discussion of Experiment 1 The outcomes disclosed the presence of an ORE across all directions of target motion. Notably, a more pronounced backward displacement was observed for targets moving upwards (as indexed with the first harmonic component), indicating a tendency for individuals to exhibit larger backward displacements when targets moved against the direction of Earth’s gravitational pull. This enhancement of the ORE for upward trajectories replicates prior findings (Kerzel & Gegenfurtner, 2004 ; Thornton, 2002 ) and demonstrates that the motion direction systematically modulates the magnitude of the effect, revealing a clear vertical anisotropy in perceived motion onset. Importantly, participants performed the task in an upright posture aligned with the gravitational vector, and the only visual information available in the background was the moving target itself. Thus, in the absence of visual contextual cues, the perceptual system appears to have drawn upon somatosensory and vestibular signals conveying implicit gravitational information, which likely contributed to the increased backward displacement observed for upward motion. In addition, we observed that the magnitude of the first harmonic component increased with longer retention times, reaching its maximum at 900 ms. This discovery of a temporal build-up in the ORE for ascending motion is novel. However, this temporal drift in spatial localization aligns with previous studies on offset spatial localization phenomena, which have shown that Representational Gravity grows with increases in retention interval (De Sá Teixeira, 2016 ; De Sá Teixeira et al., 2013 ). The present pattern suggests that uncertainty regarding the target’s onset position grows over time, prompting observers to rely progressively more on internal estimates shaped by gravitational constraints. Taken together, these findings highlight the presence of a Gravity Related Component for the ORE and support the view that this component emerges, at least in part, from an internal model of gravity (Lacquaniti et al., 2015 ; McIntyre et al., 2001 ; Zago & Lacquaniti, 2005 ). A point of concern relates to the absence of structured visual cues in the background, which leaves the influence of such cues on the Gravity Related Component unclear. The estimation of gravity—which underlies this component—is known to be a multisensory process that integrates vestibular, somatosensory, and visual signals (Seilheimer et al., 2014 ). As articulated in Gibson’s Ground Theory of Space Perception, visual space is fundamentally structured by continuous surfaces on which objects rest. Such surfaces support perceptual organization by providing a coherent framework for interpreting visual scenes (Bian & Andersen, 2010 ). According to this perspective, observers naturally rely on the ground surface as the primary spatial reference, as it offers stability, supports locomotion, resists gravity, and extends continuously to the horizon, thus establishing a strong ecological and perceptual foundation for spatial orientation (Gibson, 1950a , 1950b , 1979 ). As humans, we are continually exposed to diverse visual environments, each offering distinct types and quantities of orientation cues. Broadly, visual scenes can be categorized as either indoor or outdoor, with outdoor environments further subdivided into man-made or natural environments (Haji-Khamneh & Harris, 2010 ; Oliva & Schyns, 2000 ; Torralba & Oliva, 2003 ). Recent evidence from De Sá Teixeira et al. ( 2024 ) has demonstrated that tilted visual contexts depicting outdoor scenes significantly modulate spatial mislocalizations of offset judgement—particularly the Representational Horizon, defined as the systematic forward displacement of a moving target’s perceived offset position along the horizon implied by the visual context (Freitas & De Sá Teixeira, 2021 ). Building upon this framework, Freitas et al. ( 2025 ) has shown that the Representational Horizon is influenced by a well-specified outdoor scene composed of a ground and sky gradient, which together provide valid cues for establishing the horizon line, a prominent and ecologically meaningful feature that naturally constrains the perceived direction of gravity. While these outcomes have advanced our understanding of how visual contextual cues affect spatial orientation, they have primarily focused on offset spatial localization tasks, leaving open the question of how such cues influence onset spatial localization phenomena. To the degree that a vertical anisotropy was revealed in Experiment 1, expressed as a Gravity Related Component, it becomes pertinent to conduct a second experiment to evaluate how visual contextual cues modulate the direction of this component. Experiment 1 involved a spatial localization task with targets moving against a black uniform background devoid of visual orientation cues. The proposed second experiment will introduce a background containing relevant contextual cues that specify a downward direction along which the Gravity Related Component presumably unfolds. To promote the effectiveness of the visual context, we will replicate the visual features used by Freitas et al. ( 2025 ), namely a ground and sky gradient implying a horizon line. In the forthcoming experiment, participants will judge the onset location of targets moving in various directions against a visual background that is either aligned with the true vertical or tilted leftward or rightward by 22.5º. Based on the current literature, it is hypothesized that visual context orientation will influence the direction of the Gravity Related Component, as indexed by the first harmonic term. Experiment 2 Method Participants. Assuming an effect size of η² p = 0.15, with power set to 0.95 (with α = 0.05), an a priori power analysis, performed with the software G*Power3.1.9.4 , revealed that 17 participants would be required to detect relevant effects with a factorial design given by 3 (visual context orientation: -22.5º, 0º, or 22.5º) × 16 (target’s trajectory). Accordingly, thirty-two participants (9 males and 23 females), aged between 18 and 42 years old ( M = 23.56; SD = 6.49), signed up for the Experiment. The reward system and the participants conditions were identical to the Experiment 1. All participants did not participate in Experiment 1. The Experiment was also preapproved by the ethics committee of the University of Aveiro (Protocol 05-CE/2025). Stimuli. A single image containing a ground and sky gradient texture, implying a horizon line, was created using The Persistence of Vision Ray Tracer (POV-Ray) software and used as the visual context. This image was chosen to increase the potential effectiveness of a visual context capable of influencing onset spatial localization phenomena. The selection of this image’s attributes was influenced by the experimental findings of Experiment 1 and guided by recent research. Recent work by Freitas et al. ( 2025 ) demonstrated the efficacy of this image in eliciting a contextual effect, which significantly modulates spatial localization phenomena, namely the Representational Horizon. In addition, this visual context was selected due to its provision of photorealistic visual orientation cues, prominently featuring a discernible horizon line (a pivotal factor in determining the orientation of the visual context). Additionally, this scene serves as a plausible analogue of the visual cues encountered in everyday outdoor realistic environments, supporting potential correlations between our results and practical applications within the realm of human factors considerations. Adobe Photoshop was used to perform necessary adjustments to the selected image, ensuring its compatibility with the screen’s height (1024 pixels) and cropping it to conform to a 1:1 aspect ratio. In consideration of the participant’s ocular comfort, the luminance of the visual context was calibrated, and its opacity was reduced by half. For the spatial localization task, a black circle with a diameter of 21 pixels (about 0.71º of visual angle), surrounded by a white circular border of 1 pixel, represented the target. Apparatus, Procedure, and Design. Most of the apparatus was the same as in Experiment 1. The procedure and design were also identical to the Experiment 1 with the following exceptions. Each trial started with the presentation of a dynamic noise mask lasting for 1 second, succeeded by the introduction of a visual context comprising a ground and sky textures. The visual context covered the entirety of the visible screen area and was oriented along the vertical axis, either tilted leftward (-22.5º), rightward (22.5º), or maintained in an upright orientation (0º). One second after the presentation of the visual context, a target appeared moving towards the periphery of the visible circular window at a velocity of 256 pixels per second (about 8.54º/s). The target’s starting position and trajectory were the same as employed in Experiment 1. Its trajectory persisted for one second and as soon as it vanished, a black cursor (diameter of 7 pixels; 0.24º) appeared at the centre of the visual context. Participants were instructed to manipulate the cursor’s position using a trackball and accurately locate the perceived target’s onset position, as precisely as possible and referring to its geometric centre. The selected spatial location was confirmed by pressing the left or right button of the trackball, which also initiated the subsequent trial (see Fig. 5). The experiment followed a repeated measures design, given by 3 (visual context orientation: -22.5º, 0º, or 22.5º) x 16 (target’s trajectory), with 16 repetitions per condition, resulting in a total of 768 trials per participant. Consistent with the protocol established in Experiment 1, participants underwent several training trials and a final debriefing session. The duration of the entire experiment was about 75 minutes. Figure 5 Trials structure for the Spatial Localization Task for Experiment 2 Calculations, Hypotheses and Statistical Analyses. The same calculation procedures used in Experiment 1 were applied in Experiment 2. In Experiment 1, the constant c and the coefficient b 1 were found to characterize the ORE. Specifically, the parameter c denotes a constant displacement observed across all motion directions (Isotropic Component). The coefficients a 1 and b 1 , when considered jointly, capture directional asymmetries corresponding to an increased displacement towards one preferred direction (Gravity Related Component). Experiment 1 demonstrated that the coefficient b 1 was indicative of an increased backward displacement for ascending targets, that is, for motion occurring against the perceived direction of gravitational acceleration. Building on these findings, Experiment 2 aims to analyse how the coefficients a 1 and b 1 are modulated by the orientation of the visual context. Following the theoretical rationale outlined in the discussion of Experiment 1, it is hypothesized that the direction of the Gravity Related Component will exhibit a tilt congruent with the vertical direction implied by the orientation of the visual context (see Fig. 6 ). To statistically evaluate these hypotheses, the estimated individual values of c , harmonic coefficients a 1 - a 4 , and b 1 - b 4 were obtained from the localization responses. These values were then subjected to a mixed multivariate analysis of variance (MANOVA), with visual context orientation (− 22.5º, 0º, and 22.5º) being taken as the repeated-measure factor. In cases where the sphericity assumption was violated, adjustments to the degrees of freedom were made using the Greenhouse-Geisser correction. Results Preliminary analyses (one sample t-test) were performed and showed that across all visual context orientations (-22.5º, 0º, 22.5º), ORE was effectively characterized by a significant constant c ( p < .001 for all visual context orientations), reflecting a backward displacement for all directions, thus manifesting the Isotropic Component. Additionally, a significant b 1 coefficient ( p < .001 for all visual context orientations) was observed, indicating a systematic propensity for an increased backward displacement for ascending targets (Gravity Related Component). As anticipated, these outcomes replicate the findings of Experiment 1, showing that across both visual context scenes (absence and presence of visual cues), ORE was well described by the Isotropic Component and the Gravity Related Component. Note Data is depicted as a function of motion direction (radial axes) for the visual context tilted − 22.5º (Panel A), the vertically aligned visual context (Panel B) and the visual context tilted + 22.5º (Panel C). Inset plots depict, for each visual context orientation, the mean constant c (Isotropic Component), and the mean first harmonic terms (Gravity Related Component). Evident biases are clearly visible when looking at the polar plots (below the top insets depicting the orientations of visual context) presented in Fig. 7 . This is particularly noticeable in the increased ORE observed for targets moving ‘‘upward’’ leftward/rightward when the visual context is tilted leftward/rightward. The univariate tests revealed that visual context orientation significantly modulated coefficient a 1 , F (1.686, 52.258) = 7.413, p = .002, partial η² = 0.193 (see Fig. 7 , bottom row, right insets below the panels). No significant effects were observed for other harmonic terms with respect to visual context orientation. The a 1 coefficient, together with coefficient b 1 , specify one single direction towards which the ORE is further increased (Gravity Related Component). In the current findings, the presence of a significant a 1 coefficient observed for the ground and sky visual context discloses a pronounced leftward/rightward bias in the ORE, manifesting an increased backward displacement aligned with the inferred gravitational direction implied by the visual context orientation. Across visual context orientations, the coefficient a 1 was found to be significantly different between the leftward and rightward conditions, as indicated by pairwise post hoc comparisons ( p < .01). Discussion Experiment 2 The outcomes of Experiment 2 further corroborated the robustness of the ORE, demonstrating its presence across all target motion directions even when a visual context containing meaningful orientation cues was introduced. As in Experiment 1, a more pronounced backward displacement occurred for ascending targets, indicating that observers tend to exhibit larger backward displacements when motion proceeds against the perceived gravitational direction. Notably, a significant trend emerged in which the largest backward displacements were observed when targets ascended along the vertical direction implied by the orientation of the visual context. Thus, the findings of Experiment 2 align with our predictions and reflect that the ORE is permeable to visual cues of orientation. Consistent with previous literature on offset spatial localization phenomena which have shown that the Representational Horizon is biased towards the horizon implied by the visual context (De Sá Teixeira et al., 2024 ; Freitas et al., 2025 ; Freitas & De Sá Teixeira, 2021 ), the present results extend this body of work by showing that the perceived onset position of a moving target is also strongly and systematically shaped by the orientation of the surrounding visual context. These outcomes not only demonstrate that the direction of the Gravity Related Component was predominantly determined by the orientation of the visual context but also highlight the effectiveness of the visual background itself, composed of a well-structured ground-sky gradient that extends continuously away from the observers. These findings reinforce the critical role of ecological visual cues in modulating spatial orientation. General Discussion The present study investigated how visual gravitational motion influences the ORE and examined the contribution of visual cues to the modulation of this phenomenon. It was found that the ORE is characterized by two components: the Isotropic Component, reflecting the presence of a backward displacement across all motion directions, and the Gravity Related Component, capturing a more pronounced backward displacement observed for targets moving against the direction of gravitational pull. Notably, the Gravity Related Component aligned with the gravitational direction implied by the orientation of the visual context. This outcome bears particularly on the ecologically meaningful visual components that constituted our visual context—a visually textured ground gradient and a sparsely structured sky, implying a visual horizon line. From an ecological perspective, humans and their environments are mutually dependent. Understanding how these visual features strengthen this reciprocal relationship is essential for elucidating how the visual system supports spatial orientation. The features of the ground gradient employed here are consistent with Gibson’s principle of texture gradients, which posits that a surface texture extending away from the observer provides powerful optical information about distance, scale, and environmental layout (Gibson, 1979 ). Such information constitutes a foundational cue for spatial orientation, supporting accurate spatial judgments and facilitating navigation (Wolbers & Wiener, 2014 ). Given its central role in everyday locomotion, stability, and interaction with the environment, it is therefore unsurprising that observers relied strongly on the orientation specified by the ground gradient in the present study. In natural environments, the sky is characterized by high luminance and occupies the uppermost portion of the visual field, making it a potentially reliable cue for visual perception. The human visual system relies on prior knowledge about environmental structure, such as the assumption that light typically originates from above, to support object recognition, determine which way is up and reorient the body. This regularity, known as the “light-from-above” prior, has been documented across multiple studies (e.g., Adams, 2007 , 2008 ; Adams et al., 2004 ; Barnett-Cowan et al., 2018 ; Mamassian & Goutcher, 2001 ). Because sunlight and diffuse skylight generally come from above, the light blue-sky gradient with sparse clouds used in our visual context perhaps activated this prior by supplying ecologically valid luminance and chromatic cues consistent with natural overhead illumination. Consequently, the sky gradient may have served as an intrinsic cue, and when the entire scene was tilted, the sky component continued to appear above relative to the horizon, thereby promoting a corresponding shift in observers’ internal gravitational perception. Turning now to the horizon, the boundary between the ground and sky naturally emerges as a perceptually stable reference for spatial orientation. The functional significance of the horizon demonstrated in our study aligns with findings from applied contexts, where the presence of a visible horizon is essential for maintaining spatial stability—particularly in naval and aviation settings—because it facilitates the alignment of visual and vestibular cues and thereby reduces sensory conflict (De Thierry De Faletans et al., 2024 ; Hemmerich et al., 2020 ; Mayo et al., 2011 ). Taken together, our findings demonstrate evidence that onset spatial localization phenomena do not depend solely on vestibular input but emerges from the dynamic integration of multiple ecologically grounded visual cues. Importantly, the presence of a vertical anisotropy and its consistent alignment with the vertical direction specified by the visual context supports the view that the ORE is not merely a low-level sensory processing mislocalization. Rather, it appears to be shaped, at least in part, by top-down expectations (see Gilbert & Sigman, 2007 ) rooted in internal models of physical regularities. In everyday environments, objects rarely appear instantaneously ‘‘out of thin air’’, which indicates that motion typically must have a cause (cf. Aristotelian physics in Byrne, 2018 ). From this standpoint, for an object to be in motion, it must be launched, acquiring the internal force necessary to set it into motion. Crucially, this causal interpretation is asymmetric for upwards versus downward motion. For descending targets, the internal force and gravitational acceleration operate in the same direction, requiring less preparatory motion. Conversely, for ascending targets, the internal force and gravitational acceleration act in opposite directions, as such, a greater effort is required to launch an object upward against the gravitational direction. Within this logic, the present findings suggest that the ORE may reflect a cognitive proclivity to attribute a ‘‘natural history’’ to dynamic events, akin to the windup that precedes throwing an object, resulting in a backward overcompensation of the target’s onset location. If this account is correct, the ORE potentially reveals that the brain relies on an internal predictive model that automatically incorporates gravitational constraints when inferring the spatiotemporal origins of a moving target (e.g., Indovina et al., 2005 ; Lacquaniti et al., 2013 ; Zago et al., 2008 ; Zago & Lacquaniti, 2005 ). In this sense, the visual system may generate a coherent estimate of backward displacement based on intuitive physical principles —an instance of what has been termed intuitive physics (Vicovaro, 2021 ). To explore this interpretation further, an important limitation of the present study must be addressed. The moving target was identical across trials, such that mass-related properties were held constant. This raises the question of whether the ORE is modulated by perceived mass or heaviness. Addressing this possibility will require a future study in which targets are made to differ in their perceived mass. Such an investigation will contribute to a deeper understanding of the mechanisms underlying the ORE and clarify whether it reflects, at least in part, the influence of an internal model of gravity. Finally, the present findings suggest that visual contextual cues can shift the internal estimate of verticality, potentially pulling it away from vestibular signals. The fact that the Gravity Related Component rotated in accordance with the orientation of the visual scene strengthens the view that the internal representation of gravity is not hardwired. Rather, it is a flexible, continuously recalibrated model shaped by the interplay of multisensory cues. This interpretation is consistent with extensive evidence showing that the term ‘‘downward’’ in the direction of gravity is dynamically constructed, emerging from a complex interaction among vestibular signals in the internal ear (in particular from the otolithic organs; see, e.g., Mars et al., 2001 ; Volkening et al., 2014 ), orientation polarizing cues available in the visual scene (e.g., buildings, texture gradients in the surfaces, architectural lines, etc.; Harris et al., 2011 ; McMullen & Jolicoeur, 1992 ), and an inherent bias aligning the vertical with one’s body axes ( idiotropic vector ; Howard & Hu, 2001 ; MacNeilage et al., 2008 ; Mittelstaedt, 1983 , 1986 ). In the domain of Representational Gravity, prior studies have shown that the idiotropic vector (body’s longitudinal axis) appears to be the main vertical reference underlying the characteristic ‘‘downward’’ localization error (De Sá Teixeira, 2014 ; De Sá Teixeira & Hecht, 2014 ). In the current study, however, although the orientation of the visual context was manipulated, observers maintained a constant upright body posture. Consequently, the idiotropic vector and vestibular gravity signals remained aligned, leaving the visual scene as the only source of cue conflict. To further clarify how the ORE emerges from the dynamic interaction of sensory systems, future work should systematically examine the combined influence of visual contextual cues and body orientation. Clarifying these interactions would provide a more comprehensive understanding of how internal models of gravity are constructed and how they influence the perceived onset position of moving targets. In conclusion, the present study demonstrates that the ORE is systematically modulated by visual gravitational motion, showing both an enhanced backward displacement for ascending targets and a reliable alignment of the Gravity Related Component with the “downward” direction implied by the visual context. These observations propose that the ORE is not a fixed, low level perceptual bias but is instead permeable to high-level contextual factors, possibly reflecting the integration of environmental structures and learned expectations into cognitive representations of motion. At a conceptual level, even though speculative, the effect appears to arise from an intuitive understanding of physical principles, in which motion onset is inferred according to the forces and constraints that typically govern objects in the environment. While the precise mechanisms underlying this phenomenon remain to be fully elucidated, the present work advances current knowledge of how multisensory information contributes to the role of a hypothetical internal model of gravity in onset spatial localization phenomena. In doing so, it opens promising avenues for future inquiries into the perceptual processes that determine onset moving objects judgements. Declarations Conflicts of interest/Competing interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Ethics approval The research received prior approval from the Ethics Committee of the University of Aveiro (Protocol 05-CE/2025), and the experimental protocol was conducted in accordance with the 1964 Declaration of Helsinki and its later amendments. Consent to participate Written informed consent was obtained from all individual participants included in this study. Consent for publication Not applicable. Funding This work was supported with national funds from FCT – Portuguese Foundation for Science and Technology, under a PhD grant to the first author (2022.11875.BD). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Authors' contributions All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Rodrigo Ribeiro Freitas and Nuno Alexandre De Sá Teixeira. The first draft of the manuscript was written by Rodrigo Ribeiro Freitas and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgments: This work was supported with national funds from FCT – Portuguese Foundation for Science and Technology, under a PhD grant to the first author (2022.11875.BD) and within the supervision of the remaining authors. Data and all files used for the experimental task are available at DOI: 10.17605/OSF.IO/7QS6Z Availability of data and materials Data and all files used for the experimental task are available at DOI: 10.17605/OSF.IO/7QS6Z Code availability Not applicable. References Actis Grosso R, Stucchi N, Vacario GB (1996) On the length of trajectories for moving dots. In Fechner Day 1996: Proceedings of the 12th annual meeting of the International Society for Psychophysics (pp. 185–190) Actis-Grosso R, Stucchi N (2003) Shifting the start: Backward mislocation of the initial position of a motion. J Exp Psychol Hum Percept Perform 29(3):675–691. https://doi.org/10.1037/0096-1523.29.3.675 Adams WJ (2007) A common light-prior for visual search, shape, and reflectance judgments. J Vis 7(11):11. https://doi.org/10.1167/7.11.11 Adams WJ (2008) Frames of reference for the light-from-above prior in visual search and shape judgements. Cognition 107(1):137–150. https://doi.org/10.1016/j.cognition.2007.08.006 Adams WJ, Graf EW, Ernst MO (2004) Experience can change the ‘light-from-above’ prior. Nat Neurosci 7(10):1057–1058. https://doi.org/10.1038/nn1312 Alexander RMN (2004) Bipedal animals, and their differences from humans. J Anat 204(5):321–330. https://doi.org/10.1111/j.0021-8782.2004.00289.x Barnett-Cowan M, Ernst MO, Bülthoff HH (2018) Gravity-dependent change in the ‘light-from-above’ prior. Sci Rep 8(1):15131. https://doi.org/10.1038/s41598-018-33625-2 Bian Z, Andersen GJ (2010) The advantage of a ground surface in the representation of visual scenes. J Vis 10(8):16–16. https://doi.org/10.1167/10.8.16 Bock O, Howard IP, Money KE, Arnorld KE (1992) Accuracy of aimed arm movements in changed gravity. Aviat Space Environ Med 63:994–998 Byrne C (2018) Aristotle’s science of matter and motion. University of Toronto Clément G, Lathan C, Lockerd A (2008) Perception of depth in microgravity during parabolic flight. Acta Astronaut 63(7–10):828–832. https://doi.org/10.1016/j.actaastro.2008.01.002 Clément G, Skinner A, Lathan C (2013) Distance and Size Perception in Astronauts during Long-Duration Spaceflight. Life 3(4):524–537. https://doi.org/10.3390/life3040524 Crevecoeur F, McIntyre J, Thonnard J-L, Lefèvre P (2014) Gravity-dependent estimates of object mass underlie the generation of motor commands for horizontal limb movements. J Neurophysiol 112(2):384–392. https://doi.org/10.1152/jn.00061.2014 Dakin C, Rosenberg A (2018) Gravity estimation and verticality perception. In Handbook of Clinical Neurology (Vol. 159, pp. 43–59). Elsevier. https://doi.org/10.1016/B978-0-444-63916-5.00003-3 de la Malla C, López-Moliner J (2015) Predictive plus online visual information optimizes temporal precision in interception. J Exp Psychol Hum Percept Perform 41(5):1271–1280. https://doi.org/10.1037/xhp0000075 De Sá Teixeira N (2016) How Fast Do Objects Fall in Visual Memory? Uncovering the Temporal and Spatial Features of Representational Gravity. PLoS ONE 11(2):e0148953. https://doi.org/10.1371/journal.pone.0148953 De Sá Teixeira NA (2014) Fourier decomposition of spatial localization errors reveals an idiotropic dominance of an internal model of gravity. Vision Res 105:177–188. https://doi.org/10.1016/j.visres.2014.10.024 De Sá Teixeira NA, Freitas RR, Silva S, Taliscas T, Mateus P, Gomes A, Lima J (2024) Representational horizon and visual space orientation: An investigation into the role of visual contextual cues on spatial mislocalisations. Atten Percept Psychophys 86(4):1222–1236. https://doi.org/10.3758/s13414-023-02783-5 De Sá Teixeira NA, Hecht H (2014) The dynamic representation of gravity is suspended when the idiotropic vector is misaligned with gravity. J Vestib Res 24(4):267–279. https://doi.org/10.3233/VES-140511 De Sá Teixeira NA, Hecht H, Oliveira AM (2013) The representational dynamics of remembered projectile locations. J Exp Psychol Hum Percept Perform 39(6):1690–1699. https://doi.org/10.1037/a0031777 De Faletans T, Misericordia C, Vallier M, Duché J-M, P., Watelain E (2024) Seasickness and partial peripheral vision obstruction with versus without an artificial horizon. Displays 85:102851. https://doi.org/10.1016/j.displa.2024.102851 Freitas RR, De Sá Teixeira NA (2021) Visual space orientation and representational gravity: Contextual orientation visual cues modulate the perceptual extrapolation of motion. J Exp Psychol Hum Percept Perform 47(12):1647–1658. https://doi.org/10.1037/xhp0000962 Freitas RR, Silva S, De Sá Teixeira N (2025) The role of visual contextual cues on motion extrapolation: A single horizon line biases the Representational Horizon [Manuscript submitted for publication]. Department of Education and Psychology, University of Aveiro Freyd JJ, Finke RA (1984) Representational momentum. J Experimental Psychology: Learn Memory Cognition 10(1):126–132. https://doi.org/10.1037/0278-7393.10.1.126 Fröhlich H (1923) Über die messung der empfindungszeit. Z Für Sinnesphysiologie 54:58 Gaveau J, Paizis C, Berret B, Pozzo T, Papaxanthis C (2011) Sensorimotor adaptation of point-to-point arm movements after spaceflight: The role of internal representation of gravity force in trajectory planning. J Neurophysiol 106(2):620–629. https://doi.org/10.1152/jn.00081.2011 Gentner D (2001) Mental Models, Psychology of. In International Encyclopedia of the Social & Behavioral Sciences (pp. 9683–9687). Elsevier. https://doi.org/10.1016/B0-08-043076-7/01487-X Gibson JJ (1950a) The perception of the visual world (pp. xii, 242). Houghton Mifflin Gibson JJ (1950b) The Perception of Visual Surfaces. Am J Psychol 63(3):367. https://doi.org/10.2307/1418003 Gibson JJ (1979) The Ecological Approach to Visual Perception: Classic Edition, 1st edn. Psychology. https://doi.org/10.4324/9781315740218 Gilbert CD, Sigman M (2007) Brain States: Top-Down Influences in Sensory Processing. Neuron 54(5):677–696. https://doi.org/10.1016/j.neuron.2007.05.019 Haji-Khamneh B, Harris LR (2010) How different types of scenes affect the Subjective Visual Vertical (SVV) and the Perceptual Upright (PU). Vision Res 50(17):1720–1727. https://doi.org/10.1016/j.visres.2010.05.027 Harris LR, Jenkin M, Dyde RT, Jenkin H (2011) Enhancing visual cues to orientation. In Progress in Brain Research (Vol. 191, pp. 133–142). Elsevier. https://doi.org/10.1016/B978-0-444-53752-2.00008-4 Hecht H (2001) Regularities of the physical world and the absence of their internalization. Behav Brain Sci 24(4):608–617. https://doi.org/10.1017/S0140525X01000036 Hecht H, Bertamini M (2000) Understanding projectile acceleration. J Exp Psychol Hum Percept Perform 26(2):730–746. https://doi.org/10.1037/0096-1523.26.2.730 Hemmerich W, Keshavarz B, Hecht H (2020) Visually Induced Motion Sickness on the Horizon. Front Virtual Real 1:582095. https://doi.org/10.3389/frvir.2020.582095 Hogendoorn H (2020) Motion Extrapolation in Visual Processing: Lessons from 25 Years of Flash-Lag Debate. J Neurosci 40(30):5698–5705. https://doi.org/10.1523/JNEUROSCI.0275-20.2020 Howard IP, Hu G (2001) Visually Induced Reorientation Illusions. Perception 30(5):583–600. https://doi.org/10.1068/p3106 Hubbard TL (1990) Cognitive representation of linear motion: Possible direction and gravity effects in judged displacement. Mem Cognit 18(3):299–309. https://doi.org/10.3758/BF03213883 Hubbard TL (1995) Environmental invariants in the representation of motion: Implied dynamics and representational momentum, gravity, friction, and centripetal force. Psychon Bull Rev 2(3):322–338. https://doi.org/10.3758/BF03210971 Hubbard TL (1998) Some effects of representational friction, target size, and memory averaging on memory for vertically moving targets. Can J Experimental Psychol / Revue Canadienne de Psychologie Expérimentale 52(1):44–49. https://doi.org/10.1037/h0087278 Hubbard TL (2020) Representational gravity: Empirical findings and theoretical implications. Psychon Bull Rev 27(1):36–55. https://doi.org/10.3758/s13423-019-01660-3 Hubbard TL, Bharucha JJ (1988) Judged displacement in apparent vertical and horizontal motion. Percept Psychophys 44(3):211–221. https://doi.org/10.3758/BF03206290 Hubbard TL, Motes MA (2002) Memory for initial position: A Fröhlich Effect or an Onset Repulsion Effect? J Vis 2(7):28–28. https://doi.org/10.1167/2.7.28 Hubbard TL, Motes MA (2005) An Effect of Context on Whether Memory for Initial Position Exhibits a FröHlich Effect or an Onset Repulsion Effect. Q J Experimental Psychol Sect A 58(6):961–979. https://doi.org/10.1080/02724980443000368 Hubbard TL, Ruppel SE (2011) Effects of temporal and spatial separation on velocity and strength of illusory line motion. Atten Percept Psychophys 73(4):1133–1146. https://doi.org/10.3758/s13414-010-0081-7 Indovina I, Maffei V, Bosco G, Zago M, Macaluso E, Lacquaniti F (2005) Representation of Visual Gravitational Motion in the Human Vestibular Cortex. Science 308(5720):416–419. https://doi.org/10.1126/science.1107961 Jörges B, López-Moliner J (2017) Gravity as a Strong Prior: Implications for Perception and Action. Front Hum Neurosci 11:203. https://doi.org/10.3389/fnhum.2017.00203 Kerzel D (2002) Different localization of motion onset with pointing and relative judgements. Exp Brain Res 145(3):340–350. https://doi.org/10.1007/s00221-002-1126-5 Kerzel D, Gegenfurtner KR (2004) Spatial distortions and processing latencies in the onset repulsion and Fröhlich effects. Vision Res 44(6):577–590. https://doi.org/10.1016/j.visres.2003.10.011 Kerzel D, Müsseler J (2002) Effects of stimulus material on the Fröhlich illusion. Vision Res 42(2):181–189. https://doi.org/10.1016/S0042-6989(01)00271-1 Kirschfeld K, Kammer T (1999) The Fröhlich effect: A consequence of the interaction of visual focal attention and metacontrast. Vision Res 39(22):3702–3709. https://doi.org/10.1016/S0042-6989(99)00089-9 Lacquaniti F, Bosco G, Gravano S, Indovina I, La Scaleia B, Maffei V, Zago M (2015) Gravity in the Brain as a Reference for Space and Time Perception. Multisensory Res 28(5–6):397–426. https://doi.org/10.1163/22134808-00002471 Lacquaniti F, Bosco G, Indovina I, La Scaleia B, Maffei V, Moscatelli A, Zago M (2013) Visual gravitational motion and the vestibular system in humans. Frontiers in Integrative Neuroscience , 7 . https://doi.org/10.3389/fnint.2013.00101 Lamme VAF, Roelfsema PR (2000) The distinct modes of vision offered by feedforward and recurrent processing. Trends Neurosci 23(11):571–579. https://doi.org/10.1016/S0166-2236(00)01657-X MacNeilage PR, Ganesan N, Angelaki DE (2008) Computational Approaches to Spatial Orientation: From Transfer Functions to Dynamic Bayesian Inference. J Neurophysiol 100(6):2981–2996. https://doi.org/10.1152/jn.90677.2008 Maffei V, Indovina I, Macaluso E, Ivanenko YP, Orban A, G., Lacquaniti F (2015) Visual gravity cues in the interpretation of biological movements: Neural correlates in humans. NeuroImage 104:221–230. https://doi.org/10.1016/j.neuroimage.2014.10.006 Mamassian P, Goutcher R (2001) Prior knowledge on the illumination position. Cognition 81(1):B1–B9. https://doi.org/10.1016/S0010-0277(01)00116-0 Mars F, Popov K, Vercher J-L (2001) Supramodal effects of galvanic vestibular stimulation on the subjective vertical. NeuroReport 12(13):2991–2994. https://doi.org/10.1097/00001756-200109170-00047 Mayo AM, Wade MG, Stoffregen TA (2011) Postural Effects of the Horizon on Land and at Sea. Psychol Sci 22(1):118–124. https://doi.org/10.1177/0956797610392927 McCloskey M (1983) Intuitive Physics. Scientific American 248(4): 122 – 30 McIntyre J, Zago M, Berthoz A, Lacquaniti F (2001) Does the brain model Newton’s laws? Nat Neurosci 4(7):693–694. https://doi.org/10.1038/89477 McMullen PA, Jolicoeur P (1992) Reference frame and effects of orientation on finding the tops of rotated objects. J Exp Psychol Hum Percept Perform 18(3):807–820. https://doi.org/10.1037/0096-1523.18.3.807 Mittelstaedt H (1983) A new solution to the problem of the subjective vertical. Naturwissenschaften 70(6):272–281. https://doi.org/10.1007/BF00404833 Mittelstaedt H (1986) The subjective vertical as a function of visual and extraretinal cues. Acta Psychol 63(1):63–85. https://doi.org/10.1016/0001-6918(86)90043-0 Müsseler J, Aschersleben G (1998) Localizing the first position of a moving stimulus: The Fröhlich effect and an attention-shifting explanation. Percept Psychophys 60(4):683–695. https://doi.org/10.3758/BF03206055 Müsseler J, Neumann O (1992) Apparent distance reduction with moving stimuli (Tandem Effect): Evidence for an attention-shifting model. Psychol Res 54(4):246–266. https://doi.org/10.1007/BF01358263 Müsseler J, Tiggelbeck J (2013) The perceived onset position of a moving target: Effects of trial contexts are evoked by different attentional allocations. Atten Percept Psychophys 75(2):349–357. https://doi.org/10.3758/s13414-012-0397-6 Nijhawan R (1994) Motion extrapolation in catching. Nature 370(6487):256–257. https://doi.org/10.1038/370256b0 Nijhawan R (2002) Neural delays, visual motion and the flash-lag effect. Trends Cogn Sci 6(9):387–393. https://doi.org/10.1016/S1364-6613(02)01963-0 Nijhawan R (2008) Visual prediction: Psychophysics and neurophysiology of compensation for time delays. Behav Brain Sci 31(2):179–198. https://doi.org/10.1017/S0140525X08003804 Oliva A, Schyns PG (2000) Diagnostic Colors Mediate Scene Recognition. Cogn Psychol 41(2):176–210. https://doi.org/10.1006/cogp.1999.0728 Peirce JW (2007) PsychoPy—Psychophysics software in Python. J Neurosci Methods 162(1–2):8–13. https://doi.org/10.1016/j.jneumeth.2006.11.017 Peirce JW (2008) Generating stimuli for neuroscience using PsychoPy. Frontiers in Neuroinformatics , 2 . https://doi.org/10.3389/neuro.11.010.2008 Seilheimer RL, Rosenberg A, Angelaki DE (2014) Models and processes of multisensory cue combination. Curr Opin Neurobiol 25:38–46. https://doi.org/10.1016/j.conb.2013.11.008 Sekuler R, Armstrong R (1978) Fourier analysis of polar coordinate data in visual physiology and psychophysics. Behav Res Methods Instrum 10(1):8–14. https://doi.org/10.3758/BF03205080 Thornton IM (1999) Reconstructing dynamic events: How localization of a moving target improves over time. Investig Ophthalmol Visual Sci 40(4):S3978 Thornton IM (2002) The onset repulsion effect. Spat Vis 15(2):219–244. https://doi.org/10.1163/15685680252875183 Torralba A, Oliva A (2003) Statistics of natural image categories. Network: Comput Neural Syst 14(3):391–412. https://doi.org/10.1088/0954-898X_14_3_302 Tresilian JR (1993) Four Questions of Time to Contact: A Critical Examination of Research on Interceptive Timing. Perception 22(6):653–680. https://doi.org/10.1068/p220653 Vicovaro M (2021) Intuitive physics and cognitive algebra: A review. Eur Rev Appl Psychol 71(5):100610. https://doi.org/10.1016/j.erap.2020.100610 Vinogradova OL, Tomilovskaya ES, Kozlovskaya IB (2021) Gravity as a Factor in Evolutionary Adaptation of Animals to Living on the Earth. Hum Physiol 47(7):716–734. https://doi.org/10.1134/S0362119721070124 Volkening K, Bergmann J, Keller I, Wuehr M, Müller F, Jahn K (2014) Verticality perception during and after galvanic vestibular stimulation. Neurosci Lett 581:75–79. https://doi.org/10.1016/j.neulet.2014.08.028 Volkmann D, Baluška F (2006) Gravity: One of the driving forces for evolution. Protoplasma 229(2–4):143–148. https://doi.org/10.1007/s00709-006-0200-4 Westhoff C, Troje NF (2007) Kinematic cues for person identification from biological motion. Percept Psychophys 69(2):241–253. https://doi.org/10.3758/BF03193746 Whitney D, Cavanagh P (2000) Motion distorts visual space: Shifting the perceived position of remote stationary objects. Nat Neurosci 3(9):954–959. https://doi.org/10.1038/78878 Wolbers T, Wiener JM (2014) Challenges for identifying the neural mechanisms that support spatial navigation: The impact of spatial scale. Frontiers in Human Neuroscience , 8 . https://doi.org/10.3389/fnhum.2014.00571 Zago M, Lacquaniti F (2005) Visual perception and interception of falling objects: A review of evidence for an internal model of gravity. J Neural Eng 2(3):S198–S208. https://doi.org/10.1088/1741-2560/2/3/S04 Zago M, McIntyre J, Senot P, Lacquaniti F (2008) Internal models and prediction of visual gravitational motion. Vision Res 48(14):1532–1538. https://doi.org/10.1016/j.visres.2008.04.005 Additional Declarations The authors declare no competing interests. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8662288","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":578287916,"identity":"02167ccb-c222-424f-8dbe-5ab41368d9fc","order_by":0,"name":"Rodrigo Ribeiro Freitas","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/UlEQVRIie3RsWrDMBCA4ROCZnHJeoE0fQWDIBnqrS9iUZCXDCnZi4TBXpLMhr5ESqBzgiBd/AAeXbpmSDdTNFTxGIiVsVD9k+7g4wYB+Hx/sxBigD4AkXaIRv1ryUACUdYINjjJ06qTQEvaM5qvtw4yydP3Y/0ToX3kdWM0Y9VTTZ+by2RY7ucFXwkcljulllkyGlcipEXHFcQpA77QL4hcyVv5wMZVHNLgCoJ4/6mUMZRviuToJnFjCRKVBjePfI1Tx5VgPwcuBWLA1etdJhiWh5kuRAfppRvSmAix91F/H4z9yjx5+5pFl0kbyc4W2gFs5mymbuLz+Xz/qF/MjVMaE4bNnwAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0003-0849-9099","institution":"William James Center for Research, Department of Education and Psychology, University of Aveiro, Aveiro Portugal","correspondingAuthor":true,"prefix":"","firstName":"Rodrigo","middleName":"Ribeiro","lastName":"Freitas","suffix":""},{"id":578289912,"identity":"24254fb8-2856-44de-a6fc-d86b6af520a1","order_by":1,"name":"Samuel Silva","email":"","orcid":"","institution":"Institute of Electronics and Telematics Engineering, Department of Electronics, Telecommunications and Informatics, University of Aveiro, Aveiro Portugal","correspondingAuthor":false,"prefix":"","firstName":"Samuel","middleName":"","lastName":"Silva","suffix":""},{"id":578289913,"identity":"c0dc667b-e925-4b90-a998-8dd10a3955c5","order_by":2,"name":"Nuno Alexandre De Sá Teixeira","email":"","orcid":"","institution":"William James Center for Research, Department of Education and Psychology, University of Aveiro, Aveiro Portugal","correspondingAuthor":false,"prefix":"","firstName":"Nuno","middleName":"Alexandre De Sá","lastName":"Teixeira","suffix":""}],"badges":[],"createdAt":"2026-01-21 17:06:27","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":false,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":false,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-8662288/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8662288/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":100930735,"identity":"db298fe1-d738-4b9b-8c74-969a769529f5","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1018572,"visible":true,"origin":"","legend":"","description":"","filename":"APPVisualSpaceOrientationandtheOnsetRepulsionEffectTheRoleofVisualGravitationalMotioninModulatingSpatialMisloc.docx","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/64b8e72adf1a9a198e8fde2a.docx"},{"id":100951516,"identity":"238f9b2a-0747-4951-b579-efc6b9323d0b","added_by":"auto","created_at":"2026-01-23 07:10:44","extension":"json","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":342,"visible":true,"origin":"","legend":"","description":"","filename":"rs8662288.json","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/0bd27303fbc9a5c4253a11f1.json"},{"id":100951487,"identity":"5987fa7a-2611-4e7b-8913-5915bcd1ecc3","added_by":"auto","created_at":"2026-01-23 07:10:40","extension":"xml","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":188342,"visible":true,"origin":"","legend":"","description":"","filename":"rs86622880enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/5440fa25da1606847758e2e3.xml"},{"id":100930745,"identity":"531acc92-961f-401d-9218-078fb22f2a20","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"png","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":73549,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/aa7a50a2dde02ee8835fbab1.png"},{"id":100930750,"identity":"4e3248c7-303a-446f-95e2-d7775ab28074","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"png","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":34266,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/4d1f39d1d0d45ec3f052310a.png"},{"id":100930746,"identity":"46aa7e41-9231-4c22-8067-1cc4d839a229","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":22479,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/c8cc8a46af826786052af0c3.png"},{"id":100951812,"identity":"7de0577c-26b4-48c6-8ed4-6e21c94288f1","added_by":"auto","created_at":"2026-01-23 07:11:17","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":23307,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/20081ab48d0d2da02cf48dae.png"},{"id":100950511,"identity":"091b7362-8e85-4f41-9476-6b6a54edc06d","added_by":"auto","created_at":"2026-01-23 07:08:27","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":39830,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/26e0526c780484823da2bab1.png"},{"id":100930742,"identity":"f0102500-2f1d-4b96-a803-05a673e45376","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":57921,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/37cbf98f47d85e3d0df90ed2.png"},{"id":100952208,"identity":"56bff0b3-3572-4b24-8233-7e912b03af68","added_by":"auto","created_at":"2026-01-23 07:12:13","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":48620,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/70c2f6ed762bc19e925dd2c8.png"},{"id":100951520,"identity":"221dcd4e-2a9e-41a4-af7e-a0624e550274","added_by":"auto","created_at":"2026-01-23 07:10:44","extension":"xml","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":185224,"visible":true,"origin":"","legend":"","description":"","filename":"rs86622880structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/b9b07690e91dd7cd6be38a0c.xml"},{"id":100952001,"identity":"83db36c1-deba-47b1-b120-d2e420e321cc","added_by":"auto","created_at":"2026-01-23 07:11:40","extension":"html","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":200781,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/1de820661311c694b6bfaf81.html"},{"id":100951447,"identity":"b2f64b47-12c2-4b47-b3b6-ba8dc3ee129f","added_by":"auto","created_at":"2026-01-23 07:10:37","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":155989,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eLaboratorial Setting for the Experiments (Panel A) and Trials Structure for the Spatial Localization Task (Panel B).\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote.\u003c/em\u003e Notice that stimuli sizes are not to scale.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/c701496a764c39fd6c2d6459.jpeg"},{"id":100951323,"identity":"62e57afd-fd36-40c7-98aa-5d1f915e8be8","added_by":"auto","created_at":"2026-01-23 07:10:29","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":185890,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003ePolar Plots illustrate the expected patterns of the ORE as a function of the orientation of the target’s trajectories (θ; represented as the radial parameter)\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote.\u003c/em\u003e Rightward plots depict the underlying harmonic terms, both algebraically and graphically in polar plots.\u003c/p\u003e","description":"","filename":"floatimage227.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/481a3d3605087e292e7cf9bd.png"},{"id":100952123,"identity":"7b2c5414-4145-49bd-b63b-539f69fdcfba","added_by":"auto","created_at":"2026-01-23 07:11:58","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":110708,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eSchematic Representation of Polar plots depicting the found ORE\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote.\u003c/em\u003e Panel A: Polar plot depicting the found ORE (data markers) and the Fourier-based theoretical adjustments (lines) found for each motion direction and retention times; Panel B: Polar plot of the mean estimated parameter \u003cem\u003ec\u003c/em\u003e (Isotropic Component); Panel C: Polar plot of the mean estimated coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u003csub\u003e \u003c/sub\u003e(Gravity Related Component).\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/82e6ea3ab42114f41bfa18ac.png"},{"id":100951811,"identity":"9c1196ad-6701-45df-b186-aa1351cb5530","added_by":"auto","created_at":"2026-01-23 07:11:17","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":111059,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eMean c parameters (solid black squares and full lines) and b\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e coefficients (open triangles with dashed lines) found for each retention interval (abscissas)\u003c/em\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote.\u003c/em\u003e The vertical bars depict the standard errors of the means.\u003c/p\u003e","description":"","filename":"floatimage415.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/2079594c7b5cf5943242dcc6.png"},{"id":100930737,"identity":"76763678-8046-4c14-97ef-f17ae7f6bce1","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"jpeg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":90916,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eTrials structure for the Spatial Localization Task for Experiment 2\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage5.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/189f5511d4c4ac783f763f24.jpeg"},{"id":100930740,"identity":"c3cb302c-a871-4271-91a9-2d2503b46f39","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":119082,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003eHypothesized Scenarios for Experiment 2 with the Orientation of the Visual Context Significantly Altering the Direction of the Gravity related component (Indexed by the Coefficients of the First Harmonic Term)\u003c/em\u003e\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/cd27acf6416a150ebf9187e4.png"},{"id":100930747,"identity":"7f67441d-786d-49ab-bcf9-f795454023be","added_by":"auto","created_at":"2026-01-23 00:42:05","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":183932,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cem\u003ePolar plots of the mean ORE for each visual context orientation\u003c/em\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eNote\u003c/em\u003e\u003cstrong\u003e. \u003c/strong\u003eData is depicted as a function of motion direction (radial axes) for the visual context tilted -22.5º (Panel A), the vertically aligned visual context (Panel B) and the visual context tilted +22.5º (Panel C). Inset plots depict, for each visual context orientation, the mean constant \u003cem\u003ec\u003c/em\u003e (Isotropic Component), and the mean first harmonic terms (Gravity Related Component).\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/a8efcb94bea98d988503df0a.png"},{"id":101296955,"identity":"2ab26765-3156-45fb-a521-e6085174b548","added_by":"auto","created_at":"2026-01-28 09:23:44","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1744120,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8662288/v1/d0aeb8c1-538b-42b0-ae20-1a035eeadbe2.pdf"}],"financialInterests":"The authors declare no competing interests.","formattedTitle":"\u003cp\u003eVisual Space Orientation and the Onset Repulsion Effect: The Role of Visual Gravitational Motion in Modulating Spatial Mislocalizations\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cdiv id=\"Sec2\" class=\"Section2\"\u003e \u003ch2\u003eGravity as a reference for human perception and action\u003c/h2\u003e \u003cp\u003eIf you toss a handful of confetti into the air at a birthday celebration, you will immediately notice that each piece inevitably falls back to the ground. This simple observation illustrates the omnipresent influence of gravity, a fundamental physical force that attracts masses toward the Earth’s centre (Volkmann \u0026amp; Baluška, \u003cspan citationid=\"CR84\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Beyond its physical definition, gravity provides the primary reference for orientation, balance, and movement in all terrestrial organisms (Vinogradova et al., \u003cspan citationid=\"CR82\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Within the animal kingdom, humans have evolved a bipedal, upright posture. This vertical orientation offers numerous adaptive benefits, such as freeing our hands for object manipulation, elevating our line of sight, and enabling metabolically efficient locomotion (Alexander, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Crevecoeur et al., \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Although our ability to maintain a vertical posture confers several advantages, it also renders us less stable compared to quadrupedal locomotion, thereby increasing susceptibility to imbalance and falls. Consequently, the ability to accurately estimate our orientation relative to gravity is essential for maintaining posture and ensuring safe locomotion (Dakin \u0026amp; Rosenberg, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). In addition to its biomechanical importance, gravity profoundly shapes sensorimotor and perceptual processes. Empirical evidence shows that internal representations of gravity play a role in sensorimotor tasks, including catching (de la Malla \u0026amp; López-Moliner, \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Tresilian, \u003cspan citationid=\"CR80\" class=\"CitationRef\"\u003e1993\u003c/span\u003e), motor control (Bock et al., \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e1992\u003c/span\u003e; Gaveau et al., \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), spatial perception (Clément et al., \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2008\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2013\u003c/span\u003e), and even for the perception of motion patterns (Maffei et al., \u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Westhoff \u0026amp; Troje, \u003cspan citationid=\"CR85\" class=\"CitationRef\"\u003e2007\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eGiven that the entirety of human evolution and individual development has taken place under the influence of Earth’s gravity, the human perceptual system has become finely attuned to this ubiquitous force. Perception of gravity arises from the coordinate contribution of multisensory modalities—vision, the vestibular system (comprising the otolith organs and semicircular canals), proprioception (receptors in muscles and tendons), and other somatic cues originating from internal organs such as the kidneys and intestines (Jörges \u0026amp; López-Moliner, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Although vestibular and proprioceptive cues provide direct information about body orientation and acceleration, vision plays a crucial role in the perception of gravity by offering contextual and referential visual cues that help define the subjective sense of verticality. Visual information contributes to the establishment of visual reference frames, such as the orientation of the surrounding environment—strongly influenced by the presence of a horizon—which can modulate offset spatial mislocalizations (De Sá Teixeira et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Freitas et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Freitas \u0026amp; De Sá Teixeira, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Beyond static orientation cues, vision supplies dynamic information, enabling the visual system to infer acceleration consistent with gravitational motion.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eSystematic spatial mislocalizations shaped by gravity\u003c/h2\u003e \u003cp\u003eThese lines of reasoning converge in the domain of motion perception, which, according to psychophysical research on spatial mislocalization phenomena involving moving stimuli, is not entirely reliable. Accurately perceiving and predicting motion is crucial for effective interaction with a dynamic world. Everyday actions, such as intersecting a moving object, driving in traffic, or crossing a busy street, depend on the visual system’s ability to anticipate the future state of moving stimuli (Hogendoorn, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Nijhawan, \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e1994\u003c/span\u003e, \u003cspan citationid=\"CR70\" class=\"CitationRef\"\u003e2002\u003c/span\u003e, \u003cspan citationid=\"CR71\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). Far from functioning as a passive receiver of sensory input, the human perceptual system actively constructs predictive representations of motion to compensate for delays incurred during the transmission and cortical processing of visual information, which amount to approximately 70 ms (Lamme \u0026amp; Roelfsema, \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Without such predictive mechanisms, this neural lag would substantially impair our ability to perceive and respond adaptively in a continuously changing environment. Even under simple laboratory conditions, such as viewing a single dot moving across a blank screen, observers systematically misjudge the onset and offset locations of motion. When participants are asked to indicate the offset position of a moving target, they tend to displace it forward, in the direction of motion—Representational Momentum (Freyd \u0026amp; Finke, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e1984\u003c/span\u003e; Hubbard, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e1995\u003c/span\u003e), and downward, in the direction of gravity—Representational Gravity (Hubbard, \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1990\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Hubbard \u0026amp; Bharucha, \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e1988\u003c/span\u003e). Representational Gravity and Representational Momentum operate along separate axes for horizontally moving targets but converge along the same axis for vertically moving ones. Consequently, motion extrapolation for vertical motion differs depending on direction, being larger for descending and smaller for ascending targets (De Sá Teixeira, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). Research on Representational Gravity has explored the potential modulation of this effect by several factors, including target characteristics, display configuration, contextual information, and observer-related variables (Hubbard, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The existence of Representational Gravity is consistent with the hypothesis that neural systems have evolved to exploit invariant physical regularities, such as the constant acceleration due to gravity, through internal models of gravity that optimize perception and action (Lacquaniti et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2013\u003c/span\u003e, \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; McIntyre et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Zago \u0026amp; Lacquaniti, \u003cspan citationid=\"CR88\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eFrom forward to backward mislocalizations\u003c/h3\u003e\n\u003cp\u003eOne of the earliest reported onset mislocalizations is the Fröhlich Effect (Fröhlich, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e1923\u003c/span\u003e), in which a moving target is perceived to start ahead of its actual onset position, displaced forward along the direction of motion (Kirschfeld \u0026amp; Kammer, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e1999\u003c/span\u003e; Müsseler \u0026amp; Aschersleben, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e1998\u003c/span\u003e; Müsseler \u0026amp; Neumann, \u003cspan citationid=\"CR67\" class=\"CitationRef\"\u003e1992\u003c/span\u003e). This effect has been attributed to attentional delays in detecting motion onset (Kerzel \u0026amp; Müsseler, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Müsseler \u0026amp; Aschersleben, \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e1998\u003c/span\u003e) and to anticipatory or extrapolative mechanisms that bridge perceptual delays (Nijhawan, \u003cspan citationid=\"CR69\" class=\"CitationRef\"\u003e1994\u003c/span\u003e; Whitney \u0026amp; Cavanagh, \u003cspan citationid=\"CR86\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Interestingly, when the target velocity is reduced, the direction of mislocalization reverses. Under these slower motion conditions (\u0026lt; 15º /second), observers tend to perceive the onset position behind the true starting point—a phenomenon known as the Onset Repulsion Effect (ORE). This phenomenon manifests a displacement opposite to the direction of motion, in a position that was never physically occupied (Thornton, \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). The ORE was initially identified through studies on memory for dynamic events. In a series of experiments conducted by (Thornton, \u003cspan citationid=\"CR77\" class=\"CitationRef\"\u003e1999\u003c/span\u003e), participants observed a dot moving along a complex path with varying directions and speeds. They were then instructed to use a simple interface to reconstruct the observed event as accurately as possible, mapping out the spatial trajectory and assigning appropriate velocities to each segment. Although the primary objective was to examine how memory for dynamic events changes over time, the most significant and systematic error observed was the tendency to place the initial onset point too early along the trajectory of the event. This pattern of error is consistent with findings from Actis Grosso et al. (\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1996\u003c/span\u003e), who reported similar mislocalizations when observers tracked a dot moving along various curved and straight paths. Empirical evidence demonstrates that the ORE is more pronounced for upward than for downward motions (Thornton, \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). The magnitude of the ORE decreases with the velocity of the moving object (Kerzel \u0026amp; Gegenfurtner, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2004\u003c/span\u003e), being observed with velocities ranging from 1.96 to 15º/s (Actis-Grosso \u0026amp; Stucchi, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Additionally, the effect is confirmed regardless of whether the object is tracked with eye movements or not, and its magnitude is more pronounced when both the onset and offset points of the motion must be remembered (Thornton, \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2002\u003c/span\u003e). In related experiments, Hubbard \u0026amp; Ruppel (\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2011\u003c/span\u003e) explored the impact of cuing on the ORE with implied motions, finding that mislocalization diminished or even disappeared with the presence of a cue (Müsseler \u0026amp; Tiggelbeck, \u003cspan citationid=\"CR68\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). Further research indicates that this effect is more likely to occur when the target appears on a blank background (Hubbard \u0026amp; Motes, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), is further from a boundary (Hubbard \u0026amp; Motes, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2005\u003c/span\u003e), or when the observer's response involves pointing (Kerzel, \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2002\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eA key point for motivating this manuscript is that a comprehensive account for the ORE remains elusive. Thornton (\u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2002\u003c/span\u003e) proposed several explanatory mechanisms, including misremembering, misperception, and overcompensation. The misremembering hypothesis posits that the onset position is initially encoded accurately but becomes distorted during the retention interval between observation and report, resulting in a memory-based backward mislocalization. The misperception account suggests that observers respond to a perceptual trace that does not precisely correspond to the true onset of motion. Finally, the overcompensation hypothesis proposes that, when uncertain about the exact onset, observers choose a point further back as a correction, potentially due to real-world expectations that objects do not appear instantaneously without any prior indication. This leads observers to attribute some sort of natural history to the dynamic visual event, akin to the preparatory motion before throwing an object, causing an overcompensation of the target’s starting point. Notably, this overcompensation perspective parallels the medieval impetus theory described by McCloskey (\u003cspan citationid=\"CR61\" class=\"CitationRef\"\u003e1983\u003c/span\u003e), which itself echoes elements of Aristotelian physics (see Byrne, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\u003e), positing that motion must have a cause. Unlike Newtonian mechanics, where continuous motion requires no sustaining force, the impetus theory posits that a moving object retains an internal force, termed impetus, acquired at launch and gradually depleted over time until natural forces, such as gravity, dominate. This framework resolved a key limitation in Aristotelian physics by providing an explanation for projectile motion without invoking an external sustaining agent. For instance, a classic example demonstrated by Paulus Puchner (1577) illustrated that a cannonball moves in a straight path due to the impetus imparted by the cannon, and when this impetus is exhausted, gravitational forces cause it to fall (cf. Road Runner Physics in Gentner, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; see also Hecht, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Hecht \u0026amp; Bertamini, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). This analogy underlines the notion that an effort is required both to initiate and maintain motion, an intuition that may underlie perceptual overcompensation in dynamic visual events.\u003c/p\u003e\n\u003ch3\u003eThe Present Study\u003c/h3\u003e\n\u003cp\u003eThe present study aimed to investigate whether the perception of motion onset is systematically biased by the direction of motion in the absence of visual contextual cues, and whether such biases reflect an internalized representation of gravity acting on moving stimuli. Building on evidence that when judging the offset position of a moving target, downward mislocalizations (Representational Gravity) arise from predictive internal models of motion, and that backward displacements such as the ORE may stem from compensatory intuitions about object dynamics, we examined onset localization across multiple motion directions and temporal delays. Participants performed a spatial localization task referring to the onset position of a target moving along several possible directions against a blank uniform visual context devoid of visual cues and after an interval of 0, 300, 600, or 900 ms. By evaluating directional asymmetries and temporal dynamics in onset mislocalization, the present study aims to clarify the mechanisms underlying the ORE and to assess whether internal models of gravity shape localization even when no explicit visual gravitational cues are available.\u003c/p\u003e"},{"header":"Experiment 1","content":"\u003ch2\u003eMethod\u003c/h2\u003e\u003cp\u003e\u003cem\u003eParticipants.\u003c/em\u003e Assuming an effect size of \u003cem\u003eη²\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e = 0.15, with power set to 0.95 (with α = 0.05), an a priori power analysis, performed with the software \u003cem\u003eG*Power3.1.9.4\u003c/em\u003e, revealed that 6 participants would be required to detect relevant effects with a factorial design given by 16 (target’s trajectory) × 4 (stimulus-cursor asynchrony/retention interval: 0, 300, 600, or 900ms). To strengthen the robustness of statistical inference, thirty-two participants (9 males and 23 females), with ages ranged from 18 to 51 years old (\u003cem\u003eM\u003c/em\u003e = 23.63; \u003cem\u003eSD\u003c/em\u003e = 7.88), volunteered for the Experiment. Volunteers attending Psychology courses at the University of Aveiro received partial course credits, while non-student participants were compensated with a 5€ voucher. All participants were unaware of the Experiment’s purpose and had normal or corrected-to-normal vision, with no known vestibular deficits or history of neurologic disorders. The Experiment was preapproved by the ethics committee of the University of Aveiro (Protocol 05-CE/2025).\u003c/p\u003e\u003cp\u003e \u003cem\u003eStimuli.\u003c/em\u003e A spatial localization task was conducted within a visual context comprising a uniformly black screen devoid of any visual orientation cues. This black background was chosen, aiming to ensure neutrality and to remove any visual context that could introduce potential biases in the assessment of the ORE. It was done with the purpose of exploring the ORE in its most natural state, making it possible to verify if any tendency would be verified regarding its direction. The selected background was resized to fit the screen’s vertical height (1024 pixels) and standardized to a full-screen window aspect (1280 × 1024 pixels). The task involved a white circle target, with a diameter of 21 pixels (equivalent to about 0.71º of visual angle).\u003c/p\u003e\u003cp\u003e\u003cem\u003eApparatus, Procedure, and Design.\u003c/em\u003e Upon arrival at the laboratory, all participants received detailed explanations regarding the experimental protocols. Following this, they were requested to read and sign an informed consent before the experiment's start. Participants sat in an adjustable office chair, positioned in front of a computer screen (with a refresh rate of 60 Hz, a resolution of 1,280 x 1,024 pixels, and a physical size of 37.5 x 30 cm). The screen was adjusted such that the participant’s cyclopean eye was aligned with its centre and at a distance of 50 cm. While participants’ eye movements were not constrained, their visual field was confined to a central circular aperture with the aid of a custom-made blackboard cylinder. Its diameter matching the height of the monitor (30 cm), ensured that participants positioned their heads within it, thereby occluding their peripheral vision (see Fig.\u0026nbsp;1, panel A). To minimize potential distractions from ambient noise within the laboratory or building, participants wore noise-cancelling earmuffs during the experimental task. A brief break of several minutes was allowed once half of the task was completed. The experimental task was handled and displayed in Python using PsychoPy (Peirce, \u003cspan citationid=\"CR73\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, \u003cspan citationid=\"CR74\" class=\"CitationRef\"\u003e2008\u003c/span\u003e) and run on a personal computer. Each trial started with the presentation of a white fixation cross (26 pixels × 26 pixels, about 0.87º × 0.87º) located at the centre of the screen (1 second), subsequently replaced by a moving target represented by a white circle. The target’s starting location was randomly determined within a designated area of 410 x 410 pixels (about 13.78º × 13.78º) and proceeded to move towards the periphery of the visible circular aperture at a speed of 256 pixels per second (about 8.54º/s). The target’s initial position was chosen to ensure an adequate distance from the screen boundaries, thus minimizing potential interference with participants’ judgments of the target’s onset location (cf. Hubbard \u0026amp; Motes, \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). Target’s motion lasted for 1 second, with its trajectory varying randomly across trials between 0º (rightward motion), 22.5°, 45°, 67.5°, 90° (upward motion), 112.5°, 135°, 157.5°, 180° (leftward motion), 202.5°, 225°, 247.5°, 270° (downward motion), 292.5°, 315°, or 337.5°. After covering a total distance of about 256 pixels, the target suddenly vanished. A white circular cursor (diameter of 5 pixels; about 0.17º) appeared on the centre of the screen 0, 300, 600, or 900 ms after the target’s offset. The cursor location onscreen was controllable with a trackball, and the participants were instructed, at the beginning of the experiment, to adjust the cursor’s position to align precisely with the location where the target appeared, referring to its geometric centre. The judged onset location was confirmed by pressing either the left or right button on the trackball (see Fig.\u0026nbsp;1, panel B). The experiment followed a repeated measures design given by 16 (target’s trajectory) x 4 (stimulus-cursor asynchrony/retention interval: 0, 300, 600, or 900ms), with each condition replicated 12 times, completing a total of 768 trials per participant. Prior to the experiment start, participants could practice the task for a few trials to ensure they understood the task and could operate the trackball. After the experiment concluded, participants took part in a debriefing session where they could make any comment about the experiment and ask any question about the study. Overall, the entire experiment lasted approximately 75 minutes.\u003c/p\u003e\u003cp\u003e \u003cb\u003eFigure 1\u003c/b\u003e \u003c/p\u003e\u003cp\u003e \u003cem\u003eLaboratorial Setting for the Experiments (Panel A) and Trials Structure for the Spatial Localization Task (Panel B).\u003c/em\u003e \u003c/p\u003e\u003cp\u003e \u003cstrong\u003eNote\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eNotice that stimuli sizes are not to scale.\u003c/p\u003e\u003cp\u003e \u003cem\u003eCalculations, Hypotheses and Statistical Analyses.\u003c/em\u003e On each trial of the experiment, the horizontal and vertical differences of M-displacement were calculated. M-displacement was measured by calculating the deviation in pixels between the participant’s response and the actual onset position measured along the target’s motion axis, such that these values were used to compute the orthogonal projection of the participant’s response along the target’s trajectory. Positive numbers reflect a displacement forward (Fröhlich Effect), while negative values a backward displacement (ORE), relative to motion direction. The individual sets of M-displacements, for each experimental condition and with orientation of target’s trajectory as parameter (\u003cem\u003eθ\u003c/em\u003e), were subjected to a discrete Fourier decomposition procedure (for a comprehensive elucidation of this procedure, see Sekuler \u0026amp; Armstrong, \u003cspan citationid=\"CR76\" class=\"CitationRef\"\u003e1978\u003c/span\u003e; for an example of this procedure on offset mislocalizations, see also (De Sá Teixeira, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; De Sá Teixeira et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Freitas et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Freitas \u0026amp; De Sá Teixeira, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). For each set of M-displacements, the Fourier decomposition provides individual estimates of a constant \u003cem\u003ec\u003c/em\u003e and harmonic coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e (cosine) and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003ei\u003c/em\u003e\u003c/sub\u003e (sine) up to \u003cem\u003ei\u003c/em\u003e = 4, in accordance with:\u003c/p\u003e\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:{M}_{\\theta\\:}=c+{\\sum\\:}_{i=i}^{n}\\left({a}_{i}\\text{cos}i\\frac{\\theta\\:}{2\\pi\\:}+{b}_{i}\\text{sin}i\\frac{\\theta\\:}{2\\pi\\:}\\right)\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003e \u003cstrong\u003eNote\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eRightward plots depict the underlying harmonic terms, both algebraically and graphically in polar plots.\u003c/p\u003e\u003cp\u003eGiven the hypothesis of the existence of ORE, in Eq.\u0026nbsp;1, the constant \u003cem\u003ec\u003c/em\u003e denotes the amount of ORE observed across all motion directions (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e, rightward top plot). The coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e, when considered jointly, reflect an increased displacement towards one preferred direction (see Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e2\u003c/span\u003e, rightward bottom plot). Previous research has revealed an increased backward displacement for ascending targets, compared to descending targets (Thornton, \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2002\u003c/span\u003e), putatively due to the greater effort required to launch an object upwards against the gravitational acceleration. Based on these findings, this experiment aims to understand which parameters significantly contribute to the ORE when performing an onset spatial localization task and how these parameters are affected by the target’s trajectory. In addition, in Experiment 1, an additional goal is to study the evolution of memory for the ORE over time.\u003c/p\u003e\u003cp\u003eTo statistically evaluate the data obtained on this experiment, the estimated individual values of \u003cem\u003ec\u003c/em\u003e, harmonic coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e were obtained from the localization responses for each experiment. These values were then subjected to a mixed multivariate analysis of variance (MANOVA), with retention time (0, 300, 600, or 900 ms) being taken as the repeated-measure factor. In cases where the sphericity assumption was violated, adjustments to the degrees of freedom were made using the Greenhouse-Geisser correction.\u003c/p\u003e\u003ch3\u003eResults\u003c/h3\u003e\u003cp\u003eFigure 3, plot A, illustrates the polar plot for the mean ORE as a function of the target’s motion direction (radial lines) and the retention interval (line parameters) for the absence of visual context. Before proceeding with the main analyses, mean ORE for each target’s motion direction and retention intervals were subjected to a one-sample t-test to confirm the presence of backward perceptual displacements. These preliminary analyses revealed that within the absence of visual context, the ORE could be well described by two significant parameters (see Fig.\u0026nbsp;3, plot A). Specifically, a significant constant \u003cem\u003ec\u003c/em\u003e (\u003cem\u003ep\u003c/em\u003e \u0026lt; .001 for all retention intervals), indicates a backward displacement for all directions—which we coin the Isotropic Component (see Fig.\u0026nbsp;3, plot B). Additionally, a significant \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e coefficient (\u003cem\u003ep\u003c/em\u003e \u0026lt; .001 for all retention intervals), accounts for a more pronounced backward displacement for ascending targets—which we coin the Gravity Related Component (see Fig.\u0026nbsp;3, plot B).\u003c/p\u003e\u003cp\u003e \u003cb\u003eFigure 3\u003c/b\u003e \u003c/p\u003e\u003ch3\u003eSchematic Representation of Polar plots depicting the found ORE\u003c/h3\u003e\u003cp\u003e \u003cstrong\u003eNote\u003c/strong\u003e \u003c/p\u003e\u003cp\u003ePanel A: Polar plot depicting the found ORE (data markers) and the Fourier-based theoretical adjustments (lines) found for each motion direction and retention times; Panel B: Polar plot of the mean estimated parameter \u003cem\u003ec\u003c/em\u003e (Isotropic Component); Panel C: Polar plot of the mean estimated coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e (Gravity Related Component).\u003c/p\u003e\u003cp\u003eTo investigate the impact of retention time on the ORE, the estimated individual coefficients (\u003cem\u003ec\u003c/em\u003e, \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e) of Eq.\u0026nbsp;1 were subjected to a repeated measure MANOVA with retention interval as the within-subject factor. Retention time was found to significantly modulate the \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e parameter, \u003cem\u003eF\u003c/em\u003e(2.513, 77.907) = 3.625, \u003cem\u003ep\u003c/em\u003e = .022, \u003cem\u003epartial η²\u003c/em\u003e = 0.105, with a significant linear contrast, \u003cem\u003eF\u003c/em\u003e(1, 31) = 8.712, \u003cem\u003ep\u003c/em\u003e = .006, \u003cem\u003epartial η²\u003c/em\u003e = 0.219. Across retention interval conditions, the component \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e demonstrated a progressive increment, reaching its peak at 900 ms (\u003cem\u003eM=\u003c/em\u003e -14.25; \u003cem\u003eSD\u003c/em\u003e = 13.59) (see Fig.\u0026nbsp;4). No other harmonic terms were found to be significantly affected by the retention time.\u003c/p\u003e\u003cp\u003e \u003cb\u003eFigure 4\u003c/b\u003e \u003c/p\u003e\u003cp\u003e \u003cem\u003eMean c parameters (solid black squares and full lines) and b\u003c/em\u003e \u003csub\u003e \u003cem\u003e1\u003c/em\u003e \u003c/sub\u003e \u003cem\u003ecoefficients (open triangles with dashed lines) found for each retention interval (abscissas)\u003c/em\u003e\u003c/p\u003e\u003cp\u003e \u003cstrong\u003eNote\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eThe vertical bars depict the standard errors of the means.\u003c/p\u003e\u003ch3\u003eDiscussion of Experiment 1\u003c/h3\u003e\u003cp\u003eThe outcomes disclosed the presence of an ORE across all directions of target motion. Notably, a more pronounced backward displacement was observed for targets moving upwards (as indexed with the first harmonic component), indicating a tendency for individuals to exhibit larger backward displacements when targets moved against the direction of Earth’s gravitational pull. This enhancement of the ORE for upward trajectories replicates prior findings (Kerzel \u0026amp; Gegenfurtner, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Thornton, \u003cspan citationid=\"CR78\" class=\"CitationRef\"\u003e2002\u003c/span\u003e) and demonstrates that the motion direction systematically modulates the magnitude of the effect, revealing a clear vertical anisotropy in perceived motion onset. Importantly, participants performed the task in an upright posture aligned with the gravitational vector, and the only visual information available in the background was the moving target itself. Thus, in the absence of visual contextual cues, the perceptual system appears to have drawn upon somatosensory and vestibular signals conveying implicit gravitational information, which likely contributed to the increased backward displacement observed for upward motion. In addition, we observed that the magnitude of the first harmonic component increased with longer retention times, reaching its maximum at 900 ms. This discovery of a temporal build-up in the ORE for ascending motion is novel. However, this temporal drift in spatial localization aligns with previous studies on offset spatial localization phenomena, which have shown that Representational Gravity grows with increases in retention interval (De Sá Teixeira, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; De Sá Teixeira et al., \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The present pattern suggests that uncertainty regarding the target’s onset position grows over time, prompting observers to rely progressively more on internal estimates shaped by gravitational constraints. Taken together, these findings highlight the presence of a Gravity Related Component for the ORE and support the view that this component emerges, at least in part, from an internal model of gravity (Lacquaniti et al., \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; McIntyre et al., \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Zago \u0026amp; Lacquaniti, \u003cspan citationid=\"CR88\" class=\"CitationRef\"\u003e2005\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eA point of concern relates to the absence of structured visual cues in the background, which leaves the influence of such cues on the Gravity Related Component unclear. The estimation of gravity—which underlies this component—is known to be a multisensory process that integrates vestibular, somatosensory, and visual signals (Seilheimer et al., \u003cspan citationid=\"CR75\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). As articulated in Gibson’s Ground Theory of Space Perception, visual space is fundamentally structured by continuous surfaces on which objects rest. Such surfaces support perceptual organization by providing a coherent framework for interpreting visual scenes (Bian \u0026amp; Andersen, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2010\u003c/span\u003e). According to this perspective, observers naturally rely on the ground surface as the primary spatial reference, as it offers stability, supports locomotion, resists gravity, and extends continuously to the horizon, thus establishing a strong ecological and perceptual foundation for spatial orientation (Gibson, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e1950a\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e1950b\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). As humans, we are continually exposed to diverse visual environments, each offering distinct types and quantities of orientation cues. Broadly, visual scenes can be categorized as either indoor or outdoor, with outdoor environments further subdivided into man-made or natural environments (Haji-Khamneh \u0026amp; Harris, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Oliva \u0026amp; Schyns, \u003cspan citationid=\"CR72\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Torralba \u0026amp; Oliva, \u003cspan citationid=\"CR79\" class=\"CitationRef\"\u003e2003\u003c/span\u003e). Recent evidence from De Sá Teixeira et al. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) has demonstrated that tilted visual contexts depicting outdoor scenes significantly modulate spatial mislocalizations of offset judgement—particularly the Representational Horizon, defined as the systematic forward displacement of a moving target’s perceived offset position along the horizon implied by the visual context (Freitas \u0026amp; De Sá Teixeira, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). Building upon this framework, Freitas et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) has shown that the Representational Horizon is influenced by a well-specified outdoor scene composed of a ground and sky gradient, which together provide valid cues for establishing the horizon line, a prominent and ecologically meaningful feature that naturally constrains the perceived direction of gravity. While these outcomes have advanced our understanding of how visual contextual cues affect spatial orientation, they have primarily focused on offset spatial localization tasks, leaving open the question of how such cues influence onset spatial localization phenomena. To the degree that a vertical anisotropy was revealed in Experiment 1, expressed as a Gravity Related Component, it becomes pertinent to conduct a second experiment to evaluate how visual contextual cues modulate the direction of this component. Experiment 1 involved a spatial localization task with targets moving against a black uniform background devoid of visual orientation cues. The proposed second experiment will introduce a background containing relevant contextual cues that specify a downward direction along which the Gravity Related Component presumably unfolds. To promote the effectiveness of the visual context, we will replicate the visual features used by Freitas et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e), namely a ground and sky gradient implying a horizon line. In the forthcoming experiment, participants will judge the onset location of targets moving in various directions against a visual background that is either aligned with the true vertical or tilted leftward or rightward by 22.5º. Based on the current literature, it is hypothesized that visual context orientation will influence the direction of the Gravity Related Component, as indexed by the first harmonic term.\u003c/p\u003e"},{"header":"Experiment 2","content":"\u003ch2\u003eMethod\u003c/h2\u003e\u003cp\u003e\u003cem\u003eParticipants.\u003c/em\u003e Assuming an effect size of \u003cem\u003eη²\u003c/em\u003e\u003csub\u003e\u003cem\u003ep\u003c/em\u003e\u003c/sub\u003e = 0.15, with power set to 0.95 (with α = 0.05), an \u003cem\u003ea priori\u003c/em\u003e power analysis, performed with the software \u003cem\u003eG*Power3.1.9.4\u003c/em\u003e, revealed that 17 participants would be required to detect relevant effects with a factorial design given by 3 (visual context orientation: -22.5º, 0º, or 22.5º) × 16 (target’s trajectory). Accordingly, thirty-two participants (9 males and 23 females), aged between 18 and 42 years old (\u003cem\u003eM\u003c/em\u003e = 23.56; \u003cem\u003eSD\u003c/em\u003e = 6.49), signed up for the Experiment. The reward system and the participants conditions were identical to the Experiment 1. All participants did not participate in Experiment 1. The Experiment was also preapproved by the ethics committee of the University of Aveiro (Protocol 05-CE/2025).\u003c/p\u003e\u003cp\u003e \u003cem\u003eStimuli.\u003c/em\u003e A single image containing a ground and sky gradient texture, implying a horizon line, was created using The Persistence of Vision Ray Tracer (POV-Ray) software and used as the visual context. This image was chosen to increase the potential effectiveness of a visual context capable of influencing onset spatial localization phenomena. The selection of this image’s attributes was influenced by the experimental findings of Experiment 1 and guided by recent research. Recent work by Freitas et al. (\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e) demonstrated the efficacy of this image in eliciting a contextual effect, which significantly modulates spatial localization phenomena, namely the Representational Horizon. In addition, this visual context was selected due to its provision of photorealistic visual orientation cues, prominently featuring a discernible horizon line (a pivotal factor in determining the orientation of the visual context). Additionally, this scene serves as a plausible analogue of the visual cues encountered in everyday outdoor realistic environments, supporting potential correlations between our results and practical applications within the realm of human factors considerations. Adobe Photoshop was used to perform necessary adjustments to the selected image, ensuring its compatibility with the screen’s height (1024 pixels) and cropping it to conform to a 1:1 aspect ratio. In consideration of the participant’s ocular comfort, the luminance of the visual context was calibrated, and its opacity was reduced by half. For the spatial localization task, a black circle with a diameter of 21 pixels (about 0.71º of visual angle), surrounded by a white circular border of 1 pixel, represented the target.\u003c/p\u003e\u003cp\u003e \u003cem\u003eApparatus, Procedure, and Design.\u003c/em\u003e \u003c/p\u003e\u003cp\u003eMost of the apparatus was the same as in Experiment 1. The procedure and design were also identical to the Experiment 1 with the following exceptions. Each trial started with the presentation of a dynamic noise mask lasting for 1 second, succeeded by the introduction of a visual context comprising a ground and sky textures. The visual context covered the entirety of the visible screen area and was oriented along the vertical axis, either tilted leftward (-22.5º), rightward (22.5º), or maintained in an upright orientation (0º). One second after the presentation of the visual context, a target appeared moving towards the periphery of the visible circular window at a velocity of 256 pixels per second (about 8.54º/s). The target’s starting position and trajectory were the same as employed in Experiment 1. Its trajectory persisted for one second and as soon as it vanished, a black cursor (diameter of 7 pixels; 0.24º) appeared at the centre of the visual context. Participants were instructed to manipulate the cursor’s position using a trackball and accurately locate the perceived target’s onset position, as precisely as possible and referring to its geometric centre. The selected spatial location was confirmed by pressing the left or right button of the trackball, which also initiated the subsequent trial (see Fig.\u0026nbsp;5). The experiment followed a repeated measures design, given by 3 (visual context orientation: -22.5º, 0º, or 22.5º) x 16 (target’s trajectory), with 16 repetitions per condition, resulting in a total of 768 trials per participant. Consistent with the protocol established in Experiment 1, participants underwent several training trials and a final debriefing session. The duration of the entire experiment was about 75 minutes.\u003c/p\u003e\u003cp\u003e \u003cb\u003eFigure 5\u003c/b\u003e \u003c/p\u003e\u003ch2\u003eTrials structure for the Spatial Localization Task for Experiment 2\u003c/h2\u003e\u003cp\u003e \u003cem\u003eCalculations, Hypotheses and Statistical Analyses.\u003c/em\u003e The same calculation procedures used in Experiment 1 were applied in Experiment 2. In Experiment 1, the constant \u003cem\u003ec\u003c/em\u003e and the coefficient \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e were found to characterize the ORE. Specifically, the parameter \u003cem\u003ec\u003c/em\u003e denotes a constant displacement observed across all motion directions (Isotropic Component). The coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e, when considered jointly, capture directional asymmetries corresponding to an increased displacement towards one preferred direction (Gravity Related Component). Experiment 1 demonstrated that the coefficient \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e was indicative of an increased backward displacement for ascending targets, that is, for motion occurring against the perceived direction of gravitational acceleration. Building on these findings, Experiment 2 aims to analyse how the coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e are modulated by the orientation of the visual context. Following the theoretical rationale outlined in the discussion of Experiment 1, it is hypothesized that the direction of the Gravity Related Component will exhibit a tilt congruent with the vertical direction implied by the orientation of the visual context (see Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eTo statistically evaluate these hypotheses, the estimated individual values of \u003cem\u003ec\u003c/em\u003e, harmonic coefficients \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e, and \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e-\u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e4\u003c/em\u003e\u003c/sub\u003e were obtained from the localization responses. These values were then subjected to a mixed multivariate analysis of variance (MANOVA), with visual context orientation (− 22.5º, 0º, and 22.5º) being taken as the repeated-measure factor. In cases where the sphericity assumption was violated, adjustments to the degrees of freedom were made using the Greenhouse-Geisser correction.\u003c/p\u003e\u003ch3\u003eResults\u003c/h3\u003e\u003cp\u003ePreliminary analyses (one sample t-test) were performed and showed that across all visual context orientations (-22.5º, 0º, 22.5º), ORE was effectively characterized by a significant constant \u003cem\u003ec\u003c/em\u003e (\u003cem\u003ep\u003c/em\u003e \u0026lt; .001 for all visual context orientations), reflecting a backward displacement for all directions, thus manifesting the Isotropic Component. Additionally, a significant \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e coefficient (\u003cem\u003ep\u003c/em\u003e \u0026lt; .001 for all visual context orientations) was observed, indicating a systematic propensity for an increased backward displacement for ascending targets (Gravity Related Component). As anticipated, these outcomes replicate the findings of Experiment 1, showing that across both visual context scenes (absence and presence of visual cues), ORE was well described by the Isotropic Component and the Gravity Related Component.\u003c/p\u003e\u003cp\u003e \u003cstrong\u003eNote\u003c/strong\u003e \u003c/p\u003e\u003cp\u003eData is depicted as a function of motion direction (radial axes) for the visual context tilted − 22.5º (Panel A), the vertically aligned visual context (Panel B) and the visual context tilted + 22.5º (Panel C). Inset plots depict, for each visual context orientation, the mean constant \u003cem\u003ec\u003c/em\u003e (Isotropic Component), and the mean first harmonic terms (Gravity Related Component).\u003c/p\u003e\u003cp\u003eEvident biases are clearly visible when looking at the polar plots (below the top insets depicting the orientations of visual context) presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e7\u003c/span\u003e. This is particularly noticeable in the increased ORE observed for targets moving ‘‘upward’’ leftward/rightward when the visual context is tilted leftward/rightward. The univariate tests revealed that visual context orientation significantly modulated coefficient \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e, \u003cem\u003eF\u003c/em\u003e(1.686, 52.258) = 7.413, \u003cem\u003ep\u003c/em\u003e = .002, \u003cem\u003epartial η²\u003c/em\u003e = 0.193 (see Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e7\u003c/span\u003e, bottom row, right insets below the panels). No significant effects were observed for other harmonic terms with respect to visual context orientation. The \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e coefficient, together with coefficient \u003cem\u003eb\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e, specify one single direction towards which the ORE is further increased (Gravity Related Component). In the current findings, the presence of a significant \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e coefficient observed for the ground and sky visual context discloses a pronounced leftward/rightward bias in the ORE, manifesting an increased backward displacement aligned with the inferred gravitational direction implied by the visual context orientation. Across visual context orientations, the coefficient \u003cem\u003ea\u003c/em\u003e\u003csub\u003e\u003cem\u003e1\u003c/em\u003e\u003c/sub\u003e was found to be significantly different between the leftward and rightward conditions, as indicated by pairwise post hoc comparisons (\u003cem\u003ep\u003c/em\u003e \u0026lt; .01).\u003c/p\u003e\u003ch2\u003eDiscussion Experiment 2\u003c/h2\u003e\u003cp\u003eThe outcomes of Experiment 2 further corroborated the robustness of the ORE, demonstrating its presence across all target motion directions even when a visual context containing meaningful orientation cues was introduced. As in Experiment 1, a more pronounced backward displacement occurred for ascending targets, indicating that observers tend to exhibit larger backward displacements when motion proceeds against the perceived gravitational direction. Notably, a significant trend emerged in which the largest backward displacements were observed when targets ascended along the vertical direction implied by the orientation of the visual context. Thus, the findings of Experiment 2 align with our predictions and reflect that the ORE is permeable to visual cues of orientation. Consistent with previous literature on offset spatial localization phenomena which have shown that the Representational Horizon is biased towards the horizon implied by the visual context (De Sá Teixeira et al., \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Freitas et al., \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2025\u003c/span\u003e; Freitas \u0026amp; De Sá Teixeira, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2021\u003c/span\u003e), the present results extend this body of work by showing that the perceived onset position of a moving target is also strongly and systematically shaped by the orientation of the surrounding visual context. These outcomes not only demonstrate that the direction of the Gravity Related Component was predominantly determined by the orientation of the visual context but also highlight the effectiveness of the visual background itself, composed of a well-structured ground-sky gradient that extends continuously away from the observers. These findings reinforce the critical role of ecological visual cues in modulating spatial orientation.\u003c/p\u003e"},{"header":"General Discussion","content":"\u003cp\u003eThe present study investigated how visual gravitational motion influences the ORE and examined the contribution of visual cues to the modulation of this phenomenon. It was found that the ORE is characterized by two components: the Isotropic Component, reflecting the presence of a backward displacement across all motion directions, and the Gravity Related Component, capturing a more pronounced backward displacement observed for targets moving against the direction of gravitational pull. Notably, the Gravity Related Component aligned with the gravitational direction implied by the orientation of the visual context.\u003c/p\u003e\u003cp\u003eThis outcome bears particularly on the ecologically meaningful visual components that constituted our visual context—a visually textured ground gradient and a sparsely structured sky, implying a visual horizon line. From an ecological perspective, humans and their environments are mutually dependent. Understanding how these visual features strengthen this reciprocal relationship is essential for elucidating how the visual system supports spatial orientation. The features of the ground gradient employed here are consistent with Gibson’s principle of texture gradients, which posits that a surface texture extending away from the observer provides powerful optical information about distance, scale, and environmental layout (Gibson, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e1979\u003c/span\u003e). Such information constitutes a foundational cue for spatial orientation, supporting accurate spatial judgments and facilitating navigation (Wolbers \u0026amp; Wiener, \u003cspan citationid=\"CR87\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). Given its central role in everyday locomotion, stability, and interaction with the environment, it is therefore unsurprising that observers relied strongly on the orientation specified by the ground gradient in the present study. In natural environments, the sky is characterized by high luminance and occupies the uppermost portion of the visual field, making it a potentially reliable cue for visual perception. The human visual system relies on prior knowledge about environmental structure, such as the assumption that light typically originates from above, to support object recognition, determine which way is up and reorient the body. This regularity, known as the “light-from-above” prior, has been documented across multiple studies (e.g., Adams, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2007\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Adams et al., \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Barnett-Cowan et al., \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e; Mamassian \u0026amp; Goutcher, \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2001\u003c/span\u003e). Because sunlight and diffuse skylight generally come from above, the light blue-sky gradient with sparse clouds used in our visual context perhaps activated this prior by supplying ecologically valid luminance and chromatic cues consistent with natural overhead illumination. Consequently, the sky gradient may have served as an intrinsic cue, and when the entire scene was tilted, the sky component continued to appear above relative to the horizon, thereby promoting a corresponding shift in observers’ internal gravitational perception. Turning now to the horizon, the boundary between the ground and sky naturally emerges as a perceptually stable reference for spatial orientation. The functional significance of the horizon demonstrated in our study aligns with findings from applied contexts, where the presence of a visible horizon is essential for maintaining spatial stability—particularly in naval and aviation settings—because it facilitates the alignment of visual and vestibular cues and thereby reduces sensory conflict (De Thierry De Faletans et al., \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2024\u003c/span\u003e; Hemmerich et al., \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Mayo et al., \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Taken together, our findings demonstrate evidence that onset spatial localization phenomena do not depend solely on vestibular input but emerges from the dynamic integration of multiple ecologically grounded visual cues.\u003c/p\u003e\u003cp\u003eImportantly, the presence of a vertical anisotropy and its consistent alignment with the vertical direction specified by the visual context supports the view that the ORE is not merely a low-level sensory processing mislocalization. Rather, it appears to be shaped, at least in part, by top-down expectations (see Gilbert \u0026amp; Sigman, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2007\u003c/span\u003e) rooted in internal models of physical regularities. In everyday environments, objects rarely appear instantaneously ‘‘out of thin air’’, which indicates that motion typically must have a cause (cf. Aristotelian physics in Byrne, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). From this standpoint, for an object to be in motion, it must be launched, acquiring the internal force necessary to set it into motion. Crucially, this causal interpretation is asymmetric for upwards versus downward motion. For descending targets, the internal force and gravitational acceleration operate in the same direction, requiring less preparatory motion. Conversely, for ascending targets, the internal force and gravitational acceleration act in opposite directions, as such, a greater effort is required to launch an object upward against the gravitational direction. Within this logic, the present findings suggest that the ORE may reflect a cognitive proclivity to attribute a ‘‘natural history’’ to dynamic events, akin to the windup that precedes throwing an object, resulting in a backward overcompensation of the target’s onset location. If this account is correct, the ORE potentially reveals that the brain relies on an internal predictive model that automatically incorporates gravitational constraints when inferring the spatiotemporal origins of a moving target (e.g., Indovina et al., \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Lacquaniti et al., \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Zago et al., \u003cspan citationid=\"CR89\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Zago \u0026amp; Lacquaniti, \u003cspan citationid=\"CR88\" class=\"CitationRef\"\u003e2005\u003c/span\u003e). In this sense, the visual system may generate a coherent estimate of backward displacement based on intuitive physical principles —an instance of what has been termed intuitive physics (Vicovaro, \u003cspan citationid=\"CR81\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). To explore this interpretation further, an important limitation of the present study must be addressed. The moving target was identical across trials, such that mass-related properties were held constant. This raises the question of whether the ORE is modulated by perceived mass or heaviness. Addressing this possibility will require a future study in which targets are made to differ in their perceived mass. Such an investigation will contribute to a deeper understanding of the mechanisms underlying the ORE and clarify whether it reflects, at least in part, the influence of an internal model of gravity.\u003c/p\u003e\u003cp\u003eFinally, the present findings suggest that visual contextual cues can shift the internal estimate of verticality, potentially pulling it away from vestibular signals. The fact that the Gravity Related Component rotated in accordance with the orientation of the visual scene strengthens the view that the internal representation of gravity is not hardwired. Rather, it is a flexible, continuously recalibrated model shaped by the interplay of multisensory cues. This interpretation is consistent with extensive evidence showing that the term ‘‘downward’’ in the direction of gravity is dynamically constructed, emerging from a complex interaction among vestibular signals in the internal ear (in particular from the otolithic organs; see, e.g., Mars et al., \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; Volkening et al., \u003cspan citationid=\"CR83\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), orientation polarizing cues available in the visual scene (e.g., buildings, texture gradients in the surfaces, architectural lines, etc.; Harris et al., \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2011\u003c/span\u003e; McMullen \u0026amp; Jolicoeur, \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e1992\u003c/span\u003e), and an inherent bias aligning the vertical with one’s body axes (\u003cem\u003eidiotropic vector\u003c/em\u003e; Howard \u0026amp; Hu, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2001\u003c/span\u003e; MacNeilage et al., \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Mittelstaedt, \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e1983\u003c/span\u003e, \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e1986\u003c/span\u003e). In the domain of Representational Gravity, prior studies have shown that the idiotropic vector (body’s longitudinal axis) appears to be the main vertical reference underlying the characteristic ‘‘downward’’ localization error (De Sá Teixeira, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2014\u003c/span\u003e; De Sá Teixeira \u0026amp; Hecht, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). In the current study, however, although the orientation of the visual context was manipulated, observers maintained a constant upright body posture. Consequently, the idiotropic vector and vestibular gravity signals remained aligned, leaving the visual scene as the only source of cue conflict. To further clarify how the ORE emerges from the dynamic interaction of sensory systems, future work should systematically examine the combined influence of visual contextual cues and body orientation. Clarifying these interactions would provide a more comprehensive understanding of how internal models of gravity are constructed and how they influence the perceived onset position of moving targets.\u003c/p\u003e\u003cp\u003eIn conclusion, the present study demonstrates that the ORE is systematically modulated by visual gravitational motion, showing both an enhanced backward displacement for ascending targets and a reliable alignment of the Gravity Related Component with the “downward” direction implied by the visual context. These observations propose that the ORE is not a fixed, low level perceptual bias but is instead permeable to high-level contextual factors, possibly reflecting the integration of environmental structures and learned expectations into cognitive representations of motion. At a conceptual level, even though speculative, the effect appears to arise from an intuitive understanding of physical principles, in which motion onset is inferred according to the forces and constraints that typically govern objects in the environment. While the precise mechanisms underlying this phenomenon remain to be fully elucidated, the present work advances current knowledge of how multisensory information contributes to the role of a hypothetical internal model of gravity in onset spatial localization phenomena. In doing so, it opens promising avenues for future inquiries into the perceptual processes that determine onset moving objects judgements.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflicts of interest/Competing interests\u003c/h2\u003e \u003cp\u003eThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eEthics approval\u003c/strong\u003e \u003cp\u003e The research received prior approval from the Ethics Committee of the University of Aveiro (Protocol 05-CE/2025), and the experimental protocol was conducted in accordance with the 1964 Declaration of Helsinki and its later amendments.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to participate\u003c/strong\u003e \u003cp\u003e Written informed consent was obtained from all individual participants included in this study.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis work was supported with national funds from FCT \u0026ndash; Portuguese Foundation for Science and Technology, under a PhD grant to the first author (2022.11875.BD). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.\u003c/p\u003e\u003ch2\u003eAuthors' contributions\u003c/h2\u003e \u003cp\u003eAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Rodrigo Ribeiro Freitas and Nuno Alexandre De S\u0026aacute; Teixeira. The first draft of the manuscript was written by Rodrigo Ribeiro Freitas and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgments:\u003c/h2\u003e \u003cp\u003eThis work was supported with national funds from FCT \u0026ndash; Portuguese Foundation for Science and Technology, under a PhD grant to the first author (2022.11875.BD) and within the supervision of the remaining authors. Data and all files used for the experimental task are available at DOI: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.17605/OSF.IO/7QS6Z\u003c/span\u003e\u003cspan address=\"10.17605/OSF.IO/7QS6Z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003ch2\u003eAvailability of data and materials\u003c/h2\u003e \u003cp\u003eData and all files used for the experimental task are available at DOI: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.17605/OSF.IO/7QS6Z\u003c/span\u003e\u003cspan address=\"10.17605/OSF.IO/7QS6Z\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/p\u003e\u003ch2\u003eCode availability\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eActis Grosso R, Stucchi N, Vacario GB (1996) On the length of trajectories for moving dots. \u003cem\u003eIn Fechner Day 1996: Proceedings of the 12th annual meeting of the International Society for Psychophysics\u003c/em\u003e (pp. 185\u0026ndash;190)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eActis-Grosso R, Stucchi N (2003) Shifting the start: Backward mislocation of the initial position of a motion. J Exp Psychol Hum Percept Perform 29(3):675\u0026ndash;691. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/0096-1523.29.3.675\u003c/span\u003e\u003cspan address=\"10.1037/0096-1523.29.3.675\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdams WJ (2007) A common light-prior for visual search, shape, and reflectance judgments. J Vis 7(11):11. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1167/7.11.11\u003c/span\u003e\u003cspan address=\"10.1167/7.11.11\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdams WJ (2008) Frames of reference for the light-from-above prior in visual search and shape judgements. Cognition 107(1):137\u0026ndash;150. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.cognition.2007.08.006\u003c/span\u003e\u003cspan address=\"10.1016/j.cognition.2007.08.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAdams WJ, Graf EW, Ernst MO (2004) Experience can change the \u0026lsquo;light-from-above\u0026rsquo; prior. Nat Neurosci 7(10):1057\u0026ndash;1058. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/nn1312\u003c/span\u003e\u003cspan address=\"10.1038/nn1312\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAlexander RMN (2004) Bipedal animals, and their differences from humans. J Anat 204(5):321\u0026ndash;330. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1111/j.0021-8782.2004.00289.x\u003c/span\u003e\u003cspan address=\"10.1111/j.0021-8782.2004.00289.x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBarnett-Cowan M, Ernst MO, B\u0026uuml;lthoff HH (2018) Gravity-dependent change in the \u0026lsquo;light-from-above\u0026rsquo; prior. Sci Rep 8(1):15131. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/s41598-018-33625-2\u003c/span\u003e\u003cspan address=\"10.1038/s41598-018-33625-2\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBian Z, Andersen GJ (2010) The advantage of a ground surface in the representation of visual scenes. J Vis 10(8):16\u0026ndash;16. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1167/10.8.16\u003c/span\u003e\u003cspan address=\"10.1167/10.8.16\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBock O, Howard IP, Money KE, Arnorld KE (1992) Accuracy of aimed arm movements in changed gravity. Aviat Space Environ Med 63:994\u0026ndash;998\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eByrne C (2018) Aristotle\u0026rsquo;s science of matter and motion. University of Toronto\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCl\u0026eacute;ment G, Lathan C, Lockerd A (2008) Perception of depth in microgravity during parabolic flight. Acta Astronaut 63(7\u0026ndash;10):828\u0026ndash;832. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.actaastro.2008.01.002\u003c/span\u003e\u003cspan address=\"10.1016/j.actaastro.2008.01.002\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCl\u0026eacute;ment G, Skinner A, Lathan C (2013) Distance and Size Perception in Astronauts during Long-Duration Spaceflight. Life 3(4):524\u0026ndash;537. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/life3040524\u003c/span\u003e\u003cspan address=\"10.3390/life3040524\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCrevecoeur F, McIntyre J, Thonnard J-L, Lef\u0026egrave;vre P (2014) Gravity-dependent estimates of object mass underlie the generation of motor commands for horizontal limb movements. J Neurophysiol 112(2):384\u0026ndash;392. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1152/jn.00061.2014\u003c/span\u003e\u003cspan address=\"10.1152/jn.00061.2014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDakin C, Rosenberg A (2018) Gravity estimation and verticality perception. In \u003cem\u003eHandbook of Clinical Neurology\u003c/em\u003e (Vol. 159, pp. 43\u0026ndash;59). Elsevier. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/B978-0-444-63916-5.00003-3\u003c/span\u003e\u003cspan address=\"10.1016/B978-0-444-63916-5.00003-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ede la Malla C, L\u0026oacute;pez-Moliner J (2015) Predictive plus online visual information optimizes temporal precision in interception. J Exp Psychol Hum Percept Perform 41(5):1271\u0026ndash;1280. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/xhp0000075\u003c/span\u003e\u003cspan address=\"10.1037/xhp0000075\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe S\u0026aacute; Teixeira N (2016) How Fast Do Objects Fall in Visual Memory? Uncovering the Temporal and Spatial Features of Representational Gravity. PLoS ONE 11(2):e0148953. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1371/journal.pone.0148953\u003c/span\u003e\u003cspan address=\"10.1371/journal.pone.0148953\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe S\u0026aacute; Teixeira NA (2014) Fourier decomposition of spatial localization errors reveals an idiotropic dominance of an internal model of gravity. Vision Res 105:177\u0026ndash;188. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.visres.2014.10.024\u003c/span\u003e\u003cspan address=\"10.1016/j.visres.2014.10.024\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe S\u0026aacute; Teixeira NA, Freitas RR, Silva S, Taliscas T, Mateus P, Gomes A, Lima J (2024) Representational horizon and visual space orientation: An investigation into the role of visual contextual cues on spatial mislocalisations. Atten Percept Psychophys 86(4):1222\u0026ndash;1236. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/s13414-023-02783-5\u003c/span\u003e\u003cspan address=\"10.3758/s13414-023-02783-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe S\u0026aacute; Teixeira NA, Hecht H (2014) The dynamic representation of gravity is suspended when the idiotropic vector is misaligned with gravity. J Vestib Res 24(4):267\u0026ndash;279. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3233/VES-140511\u003c/span\u003e\u003cspan address=\"10.3233/VES-140511\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe S\u0026aacute; Teixeira NA, Hecht H, Oliveira AM (2013) The representational dynamics of remembered projectile locations. J Exp Psychol Hum Percept Perform 39(6):1690\u0026ndash;1699. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/a0031777\u003c/span\u003e\u003cspan address=\"10.1037/a0031777\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDe Faletans T, Misericordia C, Vallier M, Duch\u0026eacute; J-M, P., Watelain E (2024) Seasickness and partial peripheral vision obstruction with versus without an artificial horizon. Displays 85:102851. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.displa.2024.102851\u003c/span\u003e\u003cspan address=\"10.1016/j.displa.2024.102851\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFreitas RR, De S\u0026aacute; Teixeira NA (2021) Visual space orientation and representational gravity: Contextual orientation visual cues modulate the perceptual extrapolation of motion. J Exp Psychol Hum Percept Perform 47(12):1647\u0026ndash;1658. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/xhp0000962\u003c/span\u003e\u003cspan address=\"10.1037/xhp0000962\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFreitas RR, Silva S, De S\u0026aacute; Teixeira N (2025) \u003cem\u003eThe role of visual contextual cues on motion extrapolation: A single horizon line biases the Representational Horizon\u003c/em\u003e [Manuscript submitted for publication]. Department of Education and Psychology, University of Aveiro\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFreyd JJ, Finke RA (1984) Representational momentum. J Experimental Psychology: Learn Memory Cognition 10(1):126\u0026ndash;132. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/0278-7393.10.1.126\u003c/span\u003e\u003cspan address=\"10.1037/0278-7393.10.1.126\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFr\u0026ouml;hlich H (1923) \u0026Uuml;ber die messung der empfindungszeit. Z F\u0026uuml;r Sinnesphysiologie 54:58\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGaveau J, Paizis C, Berret B, Pozzo T, Papaxanthis C (2011) Sensorimotor adaptation of point-to-point arm movements after spaceflight: The role of internal representation of gravity force in trajectory planning. J Neurophysiol 106(2):620\u0026ndash;629. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1152/jn.00081.2011\u003c/span\u003e\u003cspan address=\"10.1152/jn.00081.2011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGentner D (2001) Mental Models, Psychology of. In \u003cem\u003eInternational Encyclopedia of the Social \u0026amp; Behavioral Sciences\u003c/em\u003e (pp. 9683\u0026ndash;9687). Elsevier. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/B0-08-043076-7/01487-X\u003c/span\u003e\u003cspan address=\"10.1016/B0-08-043076-7/01487-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGibson JJ (1950a) \u003cem\u003eThe perception of the visual world\u003c/em\u003e (pp. xii, 242). Houghton Mifflin\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGibson JJ (1950b) The Perception of Visual Surfaces. Am J Psychol 63(3):367. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.2307/1418003\u003c/span\u003e\u003cspan address=\"10.2307/1418003\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGibson JJ (1979) The Ecological Approach to Visual Perception: Classic Edition, 1st edn. Psychology. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.4324/9781315740218\u003c/span\u003e\u003cspan address=\"10.4324/9781315740218\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGilbert CD, Sigman M (2007) Brain States: Top-Down Influences in Sensory Processing. Neuron 54(5):677\u0026ndash;696. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.neuron.2007.05.019\u003c/span\u003e\u003cspan address=\"10.1016/j.neuron.2007.05.019\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaji-Khamneh B, Harris LR (2010) How different types of scenes affect the Subjective Visual Vertical (SVV) and the Perceptual Upright (PU). Vision Res 50(17):1720\u0026ndash;1727. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.visres.2010.05.027\u003c/span\u003e\u003cspan address=\"10.1016/j.visres.2010.05.027\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHarris LR, Jenkin M, Dyde RT, Jenkin H (2011) Enhancing visual cues to orientation. In \u003cem\u003eProgress in Brain Research\u003c/em\u003e (Vol. 191, pp. 133\u0026ndash;142). Elsevier. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/B978-0-444-53752-2.00008-4\u003c/span\u003e\u003cspan address=\"10.1016/B978-0-444-53752-2.00008-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHecht H (2001) Regularities of the physical world and the absence of their internalization. Behav Brain Sci 24(4):608\u0026ndash;617. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1017/S0140525X01000036\u003c/span\u003e\u003cspan address=\"10.1017/S0140525X01000036\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHecht H, Bertamini M (2000) Understanding projectile acceleration. J Exp Psychol Hum Percept Perform 26(2):730\u0026ndash;746. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/0096-1523.26.2.730\u003c/span\u003e\u003cspan address=\"10.1037/0096-1523.26.2.730\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHemmerich W, Keshavarz B, Hecht H (2020) Visually Induced Motion Sickness on the Horizon. Front Virtual Real 1:582095. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/frvir.2020.582095\u003c/span\u003e\u003cspan address=\"10.3389/frvir.2020.582095\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHogendoorn H (2020) Motion Extrapolation in Visual Processing: Lessons from 25 Years of Flash-Lag Debate. J Neurosci 40(30):5698\u0026ndash;5705. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1523/JNEUROSCI.0275-20.2020\u003c/span\u003e\u003cspan address=\"10.1523/JNEUROSCI.0275-20.2020\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoward IP, Hu G (2001) Visually Induced Reorientation Illusions. Perception 30(5):583\u0026ndash;600. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1068/p3106\u003c/span\u003e\u003cspan address=\"10.1068/p3106\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL (1990) Cognitive representation of linear motion: Possible direction and gravity effects in judged displacement. Mem Cognit 18(3):299\u0026ndash;309. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/BF03213883\u003c/span\u003e\u003cspan address=\"10.3758/BF03213883\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL (1995) Environmental invariants in the representation of motion: Implied dynamics and representational momentum, gravity, friction, and centripetal force. Psychon Bull Rev 2(3):322\u0026ndash;338. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/BF03210971\u003c/span\u003e\u003cspan address=\"10.3758/BF03210971\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL (1998) Some effects of representational friction, target size, and memory averaging on memory for vertically moving targets. Can J Experimental Psychol / Revue Canadienne de Psychologie Exp\u0026eacute;rimentale 52(1):44\u0026ndash;49. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/h0087278\u003c/span\u003e\u003cspan address=\"10.1037/h0087278\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL (2020) Representational gravity: Empirical findings and theoretical implications. Psychon Bull Rev 27(1):36\u0026ndash;55. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/s13423-019-01660-3\u003c/span\u003e\u003cspan address=\"10.3758/s13423-019-01660-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL, Bharucha JJ (1988) Judged displacement in apparent vertical and horizontal motion. Percept Psychophys 44(3):211\u0026ndash;221. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/BF03206290\u003c/span\u003e\u003cspan address=\"10.3758/BF03206290\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL, Motes MA (2002) Memory for initial position: A Fr\u0026ouml;hlich Effect or an Onset Repulsion Effect? J Vis 2(7):28\u0026ndash;28. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1167/2.7.28\u003c/span\u003e\u003cspan address=\"10.1167/2.7.28\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL, Motes MA (2005) An Effect of Context on Whether Memory for Initial Position Exhibits a Fr\u0026ouml;Hlich Effect or an Onset Repulsion Effect. Q J Experimental Psychol Sect A 58(6):961\u0026ndash;979. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1080/02724980443000368\u003c/span\u003e\u003cspan address=\"10.1080/02724980443000368\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHubbard TL, Ruppel SE (2011) Effects of temporal and spatial separation on velocity and strength of illusory line motion. Atten Percept Psychophys 73(4):1133\u0026ndash;1146. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/s13414-010-0081-7\u003c/span\u003e\u003cspan address=\"10.3758/s13414-010-0081-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIndovina I, Maffei V, Bosco G, Zago M, Macaluso E, Lacquaniti F (2005) Representation of Visual Gravitational Motion in the Human Vestibular Cortex. Science 308(5720):416\u0026ndash;419. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1126/science.1107961\u003c/span\u003e\u003cspan address=\"10.1126/science.1107961\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJ\u0026ouml;rges B, L\u0026oacute;pez-Moliner J (2017) Gravity as a Strong Prior: Implications for Perception and Action. Front Hum Neurosci 11:203. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fnhum.2017.00203\u003c/span\u003e\u003cspan address=\"10.3389/fnhum.2017.00203\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKerzel D (2002) Different localization of motion onset with pointing and relative judgements. Exp Brain Res 145(3):340\u0026ndash;350. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00221-002-1126-5\u003c/span\u003e\u003cspan address=\"10.1007/s00221-002-1126-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKerzel D, Gegenfurtner KR (2004) Spatial distortions and processing latencies in the onset repulsion and Fr\u0026ouml;hlich effects. Vision Res 44(6):577\u0026ndash;590. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.visres.2003.10.011\u003c/span\u003e\u003cspan address=\"10.1016/j.visres.2003.10.011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKerzel D, M\u0026uuml;sseler J (2002) Effects of stimulus material on the Fr\u0026ouml;hlich illusion. Vision Res 42(2):181\u0026ndash;189. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0042-6989(01)00271-1\u003c/span\u003e\u003cspan address=\"10.1016/S0042-6989(01)00271-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKirschfeld K, Kammer T (1999) The Fr\u0026ouml;hlich effect: A consequence of the interaction of visual focal attention and metacontrast. Vision Res 39(22):3702\u0026ndash;3709. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0042-6989(99)00089-9\u003c/span\u003e\u003cspan address=\"10.1016/S0042-6989(99)00089-9\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLacquaniti F, Bosco G, Gravano S, Indovina I, La Scaleia B, Maffei V, Zago M (2015) Gravity in the Brain as a Reference for Space and Time Perception. Multisensory Res 28(5\u0026ndash;6):397\u0026ndash;426. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1163/22134808-00002471\u003c/span\u003e\u003cspan address=\"10.1163/22134808-00002471\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLacquaniti F, Bosco G, Indovina I, La Scaleia B, Maffei V, Moscatelli A, Zago M (2013) Visual gravitational motion and the vestibular system in humans. \u003cem\u003eFrontiers in Integrative Neuroscience\u003c/em\u003e, \u003cem\u003e7\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fnint.2013.00101\u003c/span\u003e\u003cspan address=\"10.3389/fnint.2013.00101\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLamme VAF, Roelfsema PR (2000) The distinct modes of vision offered by feedforward and recurrent processing. Trends Neurosci 23(11):571\u0026ndash;579. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0166-2236(00)01657-X\u003c/span\u003e\u003cspan address=\"10.1016/S0166-2236(00)01657-X\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMacNeilage PR, Ganesan N, Angelaki DE (2008) Computational Approaches to Spatial Orientation: From Transfer Functions to Dynamic Bayesian Inference. J Neurophysiol 100(6):2981\u0026ndash;2996. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1152/jn.90677.2008\u003c/span\u003e\u003cspan address=\"10.1152/jn.90677.2008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMaffei V, Indovina I, Macaluso E, Ivanenko YP, Orban A, G., Lacquaniti F (2015) Visual gravity cues in the interpretation of biological movements: Neural correlates in humans. NeuroImage 104:221\u0026ndash;230. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.neuroimage.2014.10.006\u003c/span\u003e\u003cspan address=\"10.1016/j.neuroimage.2014.10.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMamassian P, Goutcher R (2001) Prior knowledge on the illumination position. Cognition 81(1):B1\u0026ndash;B9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S0010-0277(01)00116-0\u003c/span\u003e\u003cspan address=\"10.1016/S0010-0277(01)00116-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMars F, Popov K, Vercher J-L (2001) Supramodal effects of galvanic vestibular stimulation on the subjective vertical. NeuroReport 12(13):2991\u0026ndash;2994. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1097/00001756-200109170-00047\u003c/span\u003e\u003cspan address=\"10.1097/00001756-200109170-00047\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMayo AM, Wade MG, Stoffregen TA (2011) Postural Effects of the Horizon on Land and at Sea. Psychol Sci 22(1):118\u0026ndash;124. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1177/0956797610392927\u003c/span\u003e\u003cspan address=\"10.1177/0956797610392927\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcCloskey M (1983) Intuitive Physics. \u003cem\u003eScientific American 248(4): 122\u0026thinsp;\u0026ndash;\u0026thinsp;30\u003c/em\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcIntyre J, Zago M, Berthoz A, Lacquaniti F (2001) Does the brain model Newton\u0026rsquo;s laws? Nat Neurosci 4(7):693\u0026ndash;694. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/89477\u003c/span\u003e\u003cspan address=\"10.1038/89477\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMcMullen PA, Jolicoeur P (1992) Reference frame and effects of orientation on finding the tops of rotated objects. J Exp Psychol Hum Percept Perform 18(3):807\u0026ndash;820. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1037/0096-1523.18.3.807\u003c/span\u003e\u003cspan address=\"10.1037/0096-1523.18.3.807\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMittelstaedt H (1983) A new solution to the problem of the subjective vertical. Naturwissenschaften 70(6):272\u0026ndash;281. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF00404833\u003c/span\u003e\u003cspan address=\"10.1007/BF00404833\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMittelstaedt H (1986) The subjective vertical as a function of visual and extraretinal cues. Acta Psychol 63(1):63\u0026ndash;85. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/0001-6918(86)90043-0\u003c/span\u003e\u003cspan address=\"10.1016/0001-6918(86)90043-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM\u0026uuml;sseler J, Aschersleben G (1998) Localizing the first position of a moving stimulus: The Fr\u0026ouml;hlich effect and an attention-shifting explanation. Percept Psychophys 60(4):683\u0026ndash;695. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/BF03206055\u003c/span\u003e\u003cspan address=\"10.3758/BF03206055\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM\u0026uuml;sseler J, Neumann O (1992) Apparent distance reduction with moving stimuli (Tandem Effect): Evidence for an attention-shifting model. Psychol Res 54(4):246\u0026ndash;266. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/BF01358263\u003c/span\u003e\u003cspan address=\"10.1007/BF01358263\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM\u0026uuml;sseler J, Tiggelbeck J (2013) The perceived onset position of a moving target: Effects of trial contexts are evoked by different attentional allocations. Atten Percept Psychophys 75(2):349\u0026ndash;357. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/s13414-012-0397-6\u003c/span\u003e\u003cspan address=\"10.3758/s13414-012-0397-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNijhawan R (1994) Motion extrapolation in catching. Nature 370(6487):256\u0026ndash;257. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/370256b0\u003c/span\u003e\u003cspan address=\"10.1038/370256b0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNijhawan R (2002) Neural delays, visual motion and the flash-lag effect. Trends Cogn Sci 6(9):387\u0026ndash;393. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/S1364-6613(02)01963-0\u003c/span\u003e\u003cspan address=\"10.1016/S1364-6613(02)01963-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNijhawan R (2008) Visual prediction: Psychophysics and neurophysiology of compensation for time delays. Behav Brain Sci 31(2):179\u0026ndash;198. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1017/S0140525X08003804\u003c/span\u003e\u003cspan address=\"10.1017/S0140525X08003804\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOliva A, Schyns PG (2000) Diagnostic Colors Mediate Scene Recognition. Cogn Psychol 41(2):176\u0026ndash;210. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1006/cogp.1999.0728\u003c/span\u003e\u003cspan address=\"10.1006/cogp.1999.0728\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeirce JW (2007) PsychoPy\u0026mdash;Psychophysics software in Python. J Neurosci Methods 162(1\u0026ndash;2):8\u0026ndash;13. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.jneumeth.2006.11.017\u003c/span\u003e\u003cspan address=\"10.1016/j.jneumeth.2006.11.017\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeirce JW (2008) Generating stimuli for neuroscience using PsychoPy. \u003cem\u003eFrontiers in Neuroinformatics\u003c/em\u003e, \u003cem\u003e2\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/neuro.11.010.2008\u003c/span\u003e\u003cspan address=\"10.3389/neuro.11.010.2008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSeilheimer RL, Rosenberg A, Angelaki DE (2014) Models and processes of multisensory cue combination. Curr Opin Neurobiol 25:38\u0026ndash;46. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.conb.2013.11.008\u003c/span\u003e\u003cspan address=\"10.1016/j.conb.2013.11.008\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSekuler R, Armstrong R (1978) Fourier analysis of polar coordinate data in visual physiology and psychophysics. Behav Res Methods Instrum 10(1):8\u0026ndash;14. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/BF03205080\u003c/span\u003e\u003cspan address=\"10.3758/BF03205080\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThornton IM (1999) Reconstructing dynamic events: How localization of a moving target improves over time. Investig Ophthalmol Visual Sci 40(4):S3978\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eThornton IM (2002) The onset repulsion effect. Spat Vis 15(2):219\u0026ndash;244. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1163/15685680252875183\u003c/span\u003e\u003cspan address=\"10.1163/15685680252875183\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTorralba A, Oliva A (2003) Statistics of natural image categories. Network: Comput Neural Syst 14(3):391\u0026ndash;412. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1088/0954-898X_14_3_302\u003c/span\u003e\u003cspan address=\"10.1088/0954-898X_14_3_302\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTresilian JR (1993) Four Questions of Time to Contact: A Critical Examination of Research on Interceptive Timing. Perception 22(6):653\u0026ndash;680. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1068/p220653\u003c/span\u003e\u003cspan address=\"10.1068/p220653\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVicovaro M (2021) Intuitive physics and cognitive algebra: A review. Eur Rev Appl Psychol 71(5):100610. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.erap.2020.100610\u003c/span\u003e\u003cspan address=\"10.1016/j.erap.2020.100610\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVinogradova OL, Tomilovskaya ES, Kozlovskaya IB (2021) Gravity as a Factor in Evolutionary Adaptation of Animals to Living on the Earth. Hum Physiol 47(7):716\u0026ndash;734. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1134/S0362119721070124\u003c/span\u003e\u003cspan address=\"10.1134/S0362119721070124\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVolkening K, Bergmann J, Keller I, Wuehr M, M\u0026uuml;ller F, Jahn K (2014) Verticality perception during and after galvanic vestibular stimulation. Neurosci Lett 581:75\u0026ndash;79. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.neulet.2014.08.028\u003c/span\u003e\u003cspan address=\"10.1016/j.neulet.2014.08.028\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVolkmann D, Baluška F (2006) Gravity: One of the driving forces for evolution. Protoplasma 229(2\u0026ndash;4):143\u0026ndash;148. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s00709-006-0200-4\u003c/span\u003e\u003cspan address=\"10.1007/s00709-006-0200-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWesthoff C, Troje NF (2007) Kinematic cues for person identification from biological motion. Percept Psychophys 69(2):241\u0026ndash;253. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3758/BF03193746\u003c/span\u003e\u003cspan address=\"10.3758/BF03193746\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWhitney D, Cavanagh P (2000) Motion distorts visual space: Shifting the perceived position of remote stationary objects. Nat Neurosci 3(9):954\u0026ndash;959. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1038/78878\u003c/span\u003e\u003cspan address=\"10.1038/78878\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWolbers T, Wiener JM (2014) Challenges for identifying the neural mechanisms that support spatial navigation: The impact of spatial scale. \u003cem\u003eFrontiers in Human Neuroscience\u003c/em\u003e, \u003cem\u003e8\u003c/em\u003e. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3389/fnhum.2014.00571\u003c/span\u003e\u003cspan address=\"10.3389/fnhum.2014.00571\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZago M, Lacquaniti F (2005) Visual perception and interception of falling objects: A review of evidence for an internal model of gravity. J Neural Eng 2(3):S198\u0026ndash;S208. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1088/1741-2560/2/3/S04\u003c/span\u003e\u003cspan address=\"10.1088/1741-2560/2/3/S04\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZago M, McIntyre J, Senot P, Lacquaniti F (2008) Internal models and prediction of visual gravitational motion. Vision Res 48(14):1532\u0026ndash;1538. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1016/j.visres.2008.04.005\u003c/span\u003e\u003cspan address=\"10.1016/j.visres.2008.04.005\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[{"identity":"773aa034-49d1-4825-8077-413b036cd7cb","identifier":"10.13039/501100001871","name":"Fundação para a Ciência e a Tecnologia","awardNumber":"PhD grant to the first author (2022.11875.BD)","order_by":0}],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"University of Aveiro","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Onset Repulsion Effect, Motion Perception, Spatial Orientation, Vertical Anisotropy, Isotropic Component, Gravity Related Component","lastPublishedDoi":"10.21203/rs.3.rs-8662288/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8662288/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe perceived onset position of a moving target has been found to be systematically displaced backwards, in a direction opposite to motion direction, a phenomenon coined as the Onset Repulsion Effect (ORE). Of particular relevance to the present work, the ORE has been found to be increased for ascending, in comparison with descending targets, a pattern putatively due to the greater effort required to launch an object upwards against gravitational acceleration. Although this account remains speculative, it raises the possibility that the effect may reflect a \u0026lsquo;natural history\u0026rsquo; to dynamic events, akin to the windup which precedes throwing an object, resulting in a backward overcompensation of the target\u0026rsquo;s onset location. To further explore the role played by visual gravitational motion on the ORE, two experiments were conducted in which participants were required to indicate the onset location of targets moving along one out of sixteen possible trajectories. Differences between the actual and the perceived motion onset were measured and subjected to a discrete Fourier decomposition. Results disclosed an enhanced ORE for targets moving upwards (Gravity Related Component; Experiment 1), an effect that increased with longer retention intervals. Experiment 2 further demonstrated that the Gravity Related Component is tilted in congruence with the orientation of a visual background context. These findings are discussed within the framework of internal models of gravity, human spatial orientation, and their influence on visual motion perception.\u003c/p\u003e","manuscriptTitle":"Visual Space Orientation and the Onset Repulsion Effect: The Role of Visual Gravitational Motion in Modulating Spatial Mislocalizations","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-23 00:42:00","doi":"10.21203/rs.3.rs-8662288/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6fe57d74-3678-4e91-bfae-8430a78fe644","owner":[],"postedDate":"January 23rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":61530465,"name":"Psychology"},{"id":61530466,"name":"Cognitive Neuroscience"}],"tags":[],"updatedAt":"2026-01-23T00:42:00+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-23 00:42:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8662288","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8662288","identity":"rs-8662288","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}