Audiovisual speech perception provides an opportunity to investigate the mechanisms underlying multimodal processing. By using nonspeech stimuli, it is possible to investigate the degree to which audiovisual processing is specific to the speech domain. It has been shown in a match-to-sample design that matching across modalities is more difficult…

Auditory visual information equivalence in 15 mentally retarded and 15 intellectually average 12- to 13-year-olds found retarded subjects were more accurate on intra- than on intersensory tasks, whereas there was no such difference for average subjects. Tasks involving transposition were more difficult than others for the retarded children.…