Infant responses to adult happy and sad vocal and facial expressions during face-to-face interactions

We examined 5-month-olds' responses to adult facial versus vocal displays o f happy and sad expressions during face-to-face social interactions in thre e experiments. Infants interacted with adults in either happy-sad-happy or happy-happy-happy sequences. Across experiments, either facial expressions were present while presence/absence of vocal expressions was manipulated or visual access to facial expressions was blocked but vocal expressions were present throughout. Both visual attention and infant affect were recorded. Although infants looked more when vocal expressions were present, they smi led significantly more to happy than to sad facial expressions regardless o f presence or absence of the voice. In contrast, infants showed no evidence of differential responding to voices when faces were obscured; their smili ng and visual attention simply declined over time. These results extend fin dings from non-social contexts to social interactions and also indicate tha t infants may require facial expressions to be present to discriminate amon g adult vocal expressions of affect.