Fifteen-month-old infants match vocal cues to intentional actions

Fifteen-month-old infants detected a violation when an actor performed an action that did not match her preceding vocal cue: The infants looked reliably longer when the actor expressed a humorous vocal cue followed by a sweet action or expressed a sweet vocal cue followed by a humorous action, than when the vocal cue was followed by a matching action. The infants failed to detect the mismatch when one person expressed the vocal cue and another performed the action. The results suggest that by 15 months of age, infants are capable of distinguishing between two types of vocal cues and actions along the positive emotional spectrum: humor and sweetness. Furthermore, they match humorous vocal cues to humorous actions and sweet vocal cues to sweet actions only when the cues and actions are made by the same person.