McGurk effect in Finnish syllables, isolated words, and words in sentences: Effects of word meaning and sentence context

The "McGurk effect" is a robust illusion in which subject's perception of a n acoustical syllable is modified by the view of the talker's articulation. This effect is not perceived universally but, however, is experienced by t he majority of the subjects. For example, if the acoustical syllable /ba/ i s presented in synchrony with a face articulating /ga/, English-speaking su bjects typically perceive /da/ and less frequently /ga/. We studied the McG urk effect in Finnish syllables, isolated words, and words presented in sen tence context in 65 subjects. Audiovisual combinations expected to be perce ived either as meaningful words or nonwords were used. Words were also pres ented in various positions of three-word sentences in which the expected wo rd could match or mismatch with the sentence context. A strong McGurk effec t was obtained with each stimulus type. In addition, the strength of the Mc Gurk effect did not appear to be influenced by word meaning or sentence con text. These findings support the idea that audiovisual speech integration o ccurs at phonetic perceptual level before the word meaning is extracted. (C ) 1998 Elsevier Science B.V. All rights reserved.