Hearing by eye: how much spatial degradation can be tolerated?
In the McGurk effect (McGurk and MacDonald, 1976 Nature 264 746-748), illusory auditory perception is produced if the visual information from lip movements is discrepant from the auditory information from the voice. A study is reported of the tolerance of the effect to varying levels of spatial degradation (videotaped images of a speaker's face were quantised by a mosaic transform). The illusory effect systematically decreased with an increase in the coarseness of the spatial quantisation. However, even with the coarsest level (11.2 pixels/face) the illusion did not completely disappear. In addition, those participants who did not experience the illusion nevertheless showed the effects of auditory-visual interaction in their clarity ratings of the auditory stimulus. It is concluded that auditory-visual interaction in visible speech perception is based on relatively coarse-spatial-scale information.
MacDonald
J
J
Department of Psychology, University of Portsmouth, Portsmough, PO1 2DY, UK. john.macdonald@port.ac.uk
Andersen
S
S
Bachmann
T
T
D000293:Adolescent; D000328:Adult; D005260:Female; D006801:Humans; D007088:Illusions; D008085:Lipreading; D008297:Male; D013067:Speech Perception / Q000502:physiology*