Studies of the McGurk effect: implications for theories of speech perception

Studies of the McGurk effect (McGurk and MacDonald, 1976) demonstrate that observers integrate auditory information with visual information from a talker's face during speech perception. The findings from these studies pose challenges for theories of speech perception that must account for how and why the auditory and visual information are integrated. One theoretical issue concerns the objects of speech perception. Some researchers claim that the objects of speech perception are articulatory gestures while others argue that the objects are auditory in nature. The McGurk effect is often taken as evidence for gestural approaches because such theories provide a good account for why the auditory and visual information are integrated during perception. The findings from various studies of the McGurk effect, including cross-modal context effects, developmental influences and neuromagnetic measures of brain activation are reviewed. The implication of these findings are discussed with regard to whether the metric for combining the auditory and visual information is best thought of as auditory or gestural in nature.