Infants' perception of expressive behaviors: differentiation of multimodal information.

The literature on infants' perception of facial and vocal expressions, combined with data from studies on infant-directed speech, mother-infant interaction, and social referencing, supports the view that infants come to recognize the affective expressions of others through a perceptual differentiation process. Recognition of affective expressions changes from a reliance on multimodally presented information to the recognition of vocal expressions and then of facial expressions alone. Face or voice properties become differentiated and discriminated from the whole, standing for the entire emotional expression. Initially, infants detect information that potentially carries the meaning of emotional expressions; only later do infants discriminate and then recognize those expressions. The author reviews data supporting this view and draws parallels between the perceptions of affective expressions and of speech.