Nonlinear coupling dynamics within and between brains during romantic kissing as compared to joint passive tasks

Nonlinear coupling dynamics within and between brains during romantic kissing as compared to joint passive tasks | 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 Nonlinear coupling dynamics within and between brains during romantic kissing as compared to joint passive tasks Viktor Müller, Ulman Lindenberger This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7722439/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 26 Feb, 2026 Read the published version in Nonlinear Dynamics → Version 1 posted 10 You are reading this latest preprint version Abstract Interpersonal interaction shapes brain dynamics in ways that often elude traditional linear analyses. Using electroencephalography (EEG) hyperscanning and nonlinear dynamical methods, we investigated how neural complexity and coupling within and between brains differ between joint and solitary conditions across four ecologically valid contexts: romantic kissing, resting state, pendulum observation, and music listening. Fourteen romantic couples completed each task while EEG was recorded simultaneously. Linear mixed-effects models showed that joint conditions generally enhanced inter-brain coupling, with kissing producing the strongest effects—combining elevated coupling with increased complexity. Even in resting state, with eyes open or closed, coupling increased in the absence of external stimuli, suggesting internally driven partner-oriented synchrony. Chaotic pendulum motion selectively boosted mutual synchrony, likely via heightened attentional engagement, while music listening effects varied with musical style, sex, and the frequency range of spectral estimates of nonlinear measures. Psychological ratings of romantic bond, relational dominance, and kiss quality exhibited nonlinear, often U- or V-shaped, associations with neural measures. These findings extend social neuroscience by demonstrating that nonlinear hyperscanning approaches capture flexible “hyper-brain” network dynamics tuned to the affective, cognitive, and sensorimotor demands of real-world interaction. social interaction intra- and inter-brain coupling EEG dimensionality dynamic complexity nonlinear system theory romantic kissing Full Text Additional Declarations No competing interests reported. Supplementary Files SupplementaryMaterial.pdf Cite Share Download PDF Status: Published Journal Publication published 26 Feb, 2026 Read the published version in Nonlinear Dynamics → Version 1 posted Editorial decision: Revision requested 01 Nov, 2025 Reviews received at journal 21 Oct, 2025 Reviews received at journal 20 Oct, 2025 Reviewers agreed at journal 04 Oct, 2025 Reviewers agreed at journal 01 Oct, 2025 Reviewers agreed at journal 30 Sep, 2025 Reviewers invited by journal 29 Sep, 2025 Editor assigned by journal 29 Sep, 2025 Submission checks completed at journal 27 Sep, 2025 First submitted to journal 26 Sep, 2025 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. 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Using electroencephalography (EEG) hyperscanning and nonlinear dynamical methods, we investigated how neural complexity and coupling within and between brains differ between joint and solitary conditions across four ecologically valid contexts: romantic kissing, resting state, pendulum observation, and music listening. Fourteen romantic couples completed each task while EEG was recorded simultaneously. Linear mixed-effects models showed that joint conditions generally enhanced inter-brain coupling, with kissing producing the strongest effects\u0026mdash;combining elevated coupling with increased complexity. Even in resting state, with eyes open or closed, coupling increased in the absence of external stimuli, suggesting internally driven partner-oriented synchrony. Chaotic pendulum motion selectively boosted mutual synchrony, likely via heightened attentional engagement, while music listening effects varied with musical style, sex, and the frequency range of spectral estimates of nonlinear measures. Psychological ratings of romantic bond, relational dominance, and kiss quality exhibited nonlinear, often U- or V-shaped, associations with neural measures. 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