Auditory–visual speech integration by prelinguistic infants: Perception of an emergent consonant in the McGurk effect

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Abstract
The McGurk effect, in which auditory [ba] dubbed onto [ga] lip movements is perceived as “da” or “tha,” was employed in a real‐time task to investigate auditory–visual speech perception in prelingual infants. Experiments 1A and 1B established the validity of real‐time dubbing for producing the effect. In Experiment 2, 4½‐month‐olds were tested in a habituation‐test paradigm, in which an auditory–visual stimulus was presented contingent upon visual fixation of a live face. The experimental group was habituated to a McGurk stimulus (auditory [ba] visual [ga]), and the control group to matching auditory–visual [ba]. Each group was then presented with three auditory‐only test trials, [ba], [da], and [δa] (as in then). Visual‐fixation durations in test trials showed that the experimental group treated the emergent percept in the McGurk effect, [da] or [δa], as familiar (even though they had not heard these sounds previously) and [ba] as novel. For control group infants [da] and [δa] were no more familiar than [ba]. These results are consistent with infants' perception of the McGurk effect, and support the conclusion that prelinguistic infants integrate auditory and visual speech information. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 204–220, 2004.