UCLA

Beginning early in life, infants become familiar with specific kinds of voices and faces through undergoing countless repeated experiences with them. Consequently, infants quickly develop heightened sensitivity for these familiar audiovisual stimuli over the unfamiliar counterparts. In particular, infants are very familiar with happiness as it is ubiquitously present in their social environment. The present study has a two-fold objective. In a series of four studies, it aims to investigate how infants' respond to happiness across modalities and how the perception of happiness influences the way infants perceive familiar and unfamiliar faces, by measuring their eye movements on various types of faces. The first study examines the development of infants' perception of facial, vocal, and intermodal expressions of happiness and sadness in 5- and 8-month-olds. The second study examines 3- and 5-month-olds' differential response to infant-directed (ID) and adult-directed (AD) faces and how speech influences their looking behavior to faces. The third study further examines how much of infants' preferential response to ID faces can be explained by their overall preference for happy faces. Finally, the fourth study examines if infants' heightened sensitivity to happiness would affect the way they process own- and other-race faces by examining the other-race effect (ORE) in 9-month-old Caucasian infants. Overall, the present series of studies provide comprehensive body of evidence for infants' familiarity with and preference for happiness across different stages of their development within the first year of life. Furthermore, it demonstrated that the use of happiness in faces facilitated infants' discriminatory ability in both own- and other-race faces.