What Expression Could Be Found More Quickly? It Depends on Facial Identities

Visual search task was used to explore the role of facial identity in the processing of facial expression. Participants were asked to search for a happy or sad face in a crowd of emotional face pictures. Expression search was more quickly and accurate when all the faces in a display belonged to one identity than two identities. This suggested the interference of identity variance on expression recognition. At the same time the search speed for a certain expression also depended on the number of facial identities. When faces in a display belonged to one identity, a sad face among happy faces could be found more quickly than a happy face among sad faces; otherwise, when faces in a display belonged to two identities, a happy face could be found more quickly than a sad face.