Three experiments examined 4- to 10-month-olds' perception of audio-visual (A-V) temporal synchrony cues in the presence or absence of rhythmic pattern cues. Results established that infants of all ages could discriminate between two different audio-visual rhythmic events. Only 10-month-olds detected a desynchronization of the auditory and visual components of a rhythmical event. Four- to 8-month-olds could detect A-V desynchronization, but only when the audio-visual event was nonrhythmic. (Author/KB)