Abstract
Yawning, an evolutionary facial expression, is contagious in human adults (Schurmann et al, 2005). Although previous study has shown that infants do not show contagious yawning (Millen and Anderson, 2011), it remains unclear whether infants perceive yawning like other facial expressions of emotion. In this study, we first investigated whether infants could discriminate between yawning and other mouth movements by using the preferential looking method. Second, we measured the infants' hemodynamic response to presentations of yawning and other mouth movements with near-infrared spectroscopy (NIRS) in order to examine the neural processing in their temporal areas. We hypothesized that yawning would induce higher activation in the temporal areas, which are sensitive to facial expressions of emotion. In Experiment 1, we tested 3- to 8- month-old infants' visual preference for the yawning movement as compared to the mouth movement. We presented yawning and mouth movements, tongue moved sideways against cheeks, of two females, side by side, and found that all infants showed significant preference for the yawning over the mouth movement, but that such preference disappeared when these two movements were inverted. These results suggest that infants discriminate between the yawning movement and the mouth movement from 3 months of age. In Experiment 2, we measured 5- to 8-month-old infants' hemodynamic response in the bilateral temporal areas during the presentation of yawning and mouth movements. In each trial, infants were presented with a sequence of two different females' facial movement. The hemodynamic response to the yawning and the mouth movement were contrasted against the activation during the baseline period. We found that 5- to 8- month-old infants showed higher activation for yawning than the mouth movement in the bilateral temporal areas. This indicates the possibility that the bilateral temporal areas are involved in the processing of yawning perception in infants.
Meeting abstract presented at VSS 2017