Infants' use of synchronized visual information to separate streams of speech.

In 4 studies, 7.5-month-olds used synchronized visual-auditory correlations to separate a target speech stream when a distractor passage was presented at equal loudness. Infants succeeded in a segmentation task (using the head-turn preference procedure with video familiarization) when a video of the talker's face was synchronized with the target passage (Experiment 1, N = 30). Infants did not succeed in this task when an unsynchronized (Experiment 2, N = 30) or static (Experiment 3, N = 30) face was presented during familiarization. Infants also succeeded when viewing a synchronized oscilloscope pattern (Experiment 4, N = 26), suggesting that their ability to use visual information is related to domain-general sensitivities to any synchronized auditory-visual correspondence.