Affective arousal explains infant gaze following under various social context

Gaze following is fundamental to human sociocognitive development, such as language and cultural learning. Previous studies have revealed that infant gaze following is not a reflexive orienting to adults eye movement. Instead, infants adaptively modulate gaze following behaviour depending on social contexts. However, the neurophysiological mechanisms underlying contextual modulation of gaze following remain unclear. We tested whether contextual modulation of infant gaze following is mediated by the infants heart rate, which is hypothesised to indicate the calculation of action value. Forty-one 6- to 9-month-old infants participated in this study. Infants observed either a reliable face, which gazed toward the location of an object, or an unreliable face, which gazed away from the location of an object. Then, the infants watched a video of the same model making eye contact or not showing any ostensive signals, before shifting her gaze toward one of two objects. We revealed that reliability and eye contact independently increased heart rates, which then fully mediate the effect of these social cues on the frequency of infant gaze following. Results suggest that each social cue independently enhances physiological arousal which then accumulatively predicts the likelihood of infant gaze following behaviour.