One-year old infants control bottom-up saliencies to purposely sustain attention

Salient stimuli attract gaze [1,2]. Mature perceivers internally suppress salient distractors to purposefully sustain attention on a visual target. Infants’ abilities to purposefully sustain gaze on an object, often measured in the context of play, is also assumed to require the internal suppression of distractors and is considered an early marker and risk point in the development of the internal regulatory processes mediated by the pre-frontal cortex [3,4]. Here we show that sustained attention by one-year-old infants includes a behavior-driven increase in the external salience of the target. Using head-mounted eye trackers, we measured infants’ gaze during object play and the momentary visual size of objects in the infant’s field of view. Visual size is well-known to robustly attract gaze [1]. We found that when infants directed gaze to an object, there was a simultaneous change in the the spatial relation of the head to the attended object increasing the target’s visual size relative to distractors. The onset, duration, and offset of the increased salience was time-locked with the onset, duration and offset of infant gaze to the object. The findings challenge characterizations of infant attention as a competition between bottom-up and top-down control and implicate instead a collaboration in which top-down goals drive infant’s externally-directed behaviors that suppress the salience of distractors at input. The top-down control of attention through externally directed behavior may serve as the training ground –and risk factor – in the development of internal control.