Auditory-visual intermodal matching by a chimpanzee (Pan troglodytes)

Auditory-visual intermodal information processing was studied in a female chimpanzee. Following the presentation of a recorded sound, the subject had to select, from two alternatives, a photograph that corresponded to the sample sound. Various human voices and sounds produced with objects served as auditory sample stimuli. Photographs of speakers or the sound sources of auditory stimuli served as visual comparison stimuli. When the choice alternatives consisted of a picture of a human and an object, the subject showed a generalization of performance, even when the particular auditory and visual stimuli were presented for the first time. The matching performance of the subject was significantly better when novel stimuli were presented as sample or comparison stimuli than when the trial consisted of familiar stimuli. This suggested that the novelty of stimuli facilitated the subject's performance. In sum, the chimpanzee learned to match an auditory stimulus to the comparison visual stimulus, but intermodal processing was characterized by the deterioration of matching performance with familiar stimuli.