Infants' responses to interactive gaze-contingent faces in a novel and naturalistic eye-tracking paradigm.

Face scanning is an important skill that takes place in a highly interactive context embedded within social interaction. However, previous research has studied face scanning using noninteractive stimuli. We aimed to study face scanning and social interaction in infancy in a more ecologically valid way by providing infants with a naturalistic and socially engaging experience. We developed a novel gaze-contingent eye-tracking paradigm in which infants could interact with face stimuli. Responses (socially engaging/socially disengaging) from faces were contingent on infants' eye movements. We collected eye-tracking and behavioral data of 162 (79 male, 83 female) 6-, 9- and 12-month-old infants. All infants showed a clear preference for looking at the eyes relative to the mouth. Contingency was learned implicitly, and infants were more likely to show behavioral responses (e.g., smiling, pointing) when receiving socially engaging responses. Infants' responses were also more often congruent with the actors' responses. Additionally, our large sample allowed us to look at the ranges of behavior on our task, and we identified a small number of infants who displayed deviant behaviors. We discuss these findings in relation to data collected from a small sample (N = 11) of infants considered to be at-risk for autism spectrum disorders. Our results demonstrate the versatility of the gaze-contingency eye-tracking paradigm, allowing for a more nuanced and complex investigation of face scanning as it happens in real-life interaction. As we provide additional measures of contingency learning and reciprocity, our task holds the potential to investigate atypical neurodevelopment within the first year of life. (PsycINFO Database Record (c) 2019 APA, all rights reserved).