Social Smile

The social smile is a developmental milestone in early infancy, typically emerging between about six and eight weeks of age, marking the point at which an infant begins to smile specifically and reliably in response to external social stimuli, particularly a caregiver's face or voice, rather than producing only the earlier, so-called reflexive or spontaneous smiles that newborns display from birth, which occur unpredictably, often during sleep or drowsy states, and are generally understood to reflect internal neurological activity rather than any social response to another person. Developmental researchers distinguish the two kinds of smiling by their timing, consistency, and trigger, since the true social smile appears specifically and repeatedly in response to a recognized social partner and tends to be accompanied by other emerging social behaviors, such as increased eye contact and vocalizing, whereas the earlier reflexive smile can occur with no external social trigger present at all. The emergence of the social smile is widely regarded by developmental psychologists and pediatricians as an important early sign of typical social and emotional development, since it signals that the infant has begun to recognize and respond preferentially to human faces and voices, and it plays a meaningful role in strengthening the early bond between infant and caregiver by rewarding the caregiver's own attention and interaction with a clear, emotionally engaging response, helping to establish the kind of responsive, back-and-forth social exchange thought to support the formation of a secure attachment relationship.