J. A. Jones
K. G. Munhall
Dept. of Psychol., Queen's Univ., Kingston, ON K7L 3N6, Canada
The influence of the spatial position of the acoustic signal in audiovisual speech perception was investigated in a series of experiments using the McGurk effect. Subjects viewed video disk recordings of faces producing visual VCV nonsense syllables while simultaneous acoustic VCV stimuli were presented from one of 7 different speakers locations. The speakers were positioned in a semicircular array in front of the subject. In separate studies subjects were required to name the intervocalic consonant, indicate the location of the sound source using a computerized pentiometer system, or perform both tasks. Preliminary results suggest that the subjects' ability to localize the position of the auditory stimulus was influenced by the presence of a visual stimulus. Specifically, subjects tended to localize the sound closer to the position of the monitor showing the visual stimulus. However the strength of the McGurk effect was not influenced by the spatial position of the sound source. Subjects perceived the visual /g/ and the auditory /b/ combination as /d/ equally often at all sound locations. The independence of the ventriloquist effect and audiovisual integration in the perception of the McGurk effect will be discussed in terms of spatial constraints on the cross-modal perception of speech.