T Rowan Candy¹, Jaswanth Boppana¹, Zachary Petroff¹, Philip McAdams¹, Stephanie Biehn¹, Sarah Freeman¹, Bhagya Marella¹, Victoria Tellez¹; ¹Indiana University

Purpose: Human infants begin to learn about and interact with their environment during the first months after birth. Experience across the visual field during this period contributes to activity-dependent maturation throughout the visual system. The goal of this study was to characterize the distribution of image statistics around the fixation point during infants’ head-free natural experience. Methods: Participants aged 2-12 months wore head-mounted scene and binocular eye-tracking cameras (a modified Pupil Labs Core system) while engaging in naturalistic behavior in an 8ftx8ft home-like lab environment. Binocular fixations ≥100ms were identified in the eye movement recordings using a dispersion algorithm, and then RMS luminance and chromatic contrast, color saturation and entropy statistics were averaged around these fixation points in the calibrated scene images for each infant and age group (2-3 (n=25), 5-6(n=31), 8-9(n=29) & 11-12(n=12) months). These statistics were also computed for the same locations in randomly selected images from the same age group for baseline comparison. Results: A total of more than 2 hours of video were recorded for each age group. Comparison between fixated and randomly paired images indicated that the image statistics all decreased in mean magnitude monotonically with eccentricity from the point of fixation for all age groups, across the analysis radius of 20deg. These distributions were relatively consistent across age despite the dramatic changes in motor behavior in free play activities with age. Conclusions: These data suggest that young infants demonstrate selective fixation of the more visible regions of their natural environment and that fixation behavior becomes more complex over the first months after birth, although not to the extent that might be predicted by their gross motor development. The co-location of the studied image statistics in the scene likely contributes to consistent behavior.

Acknowledgements: NEI R01 EY032897