Date of Award

Spring 1981

Project Type


Program or Major


Degree Name

Doctor of Philosophy


A substantial but contradictory literature on intersensory effects exists. Studies have been reported showing facilitation of sensitivity in one modality when other modalities are stimulated, as have studies showing inhibition of sensitivity in one modality when other modalities are stimulated. Studies reporting no effects whatever of multimodal stimulation have also been reported. This literature is reviewed in detail.

A recent series of experiments by Warren and his colleagues report a facilitating effect of simultaneous visual facilitation on the variability of responding in an auditory localization task. They hypothesize that the presence of visual texture in the light in conjunction with eye movements makes possible a more precise visual, and hence auditory, localization.

A series of nine experiments was conducted. In one experiment, auditory frequency discrimination was tested under three levels of illumination: light with texture, dark, and light without texture. No differences across illumination conditions were observed. The other eight experiments were designed to test for the necessity of visual texture in the visual facilitation of auditory localization by comparing performance in the light with texture condition to that in the light without texture condition. A variety of methods to measure localization was used, including the method of constant stimuli, pointing with a rigid rod, pointing with the arm and hand, and a signal detection paradigm. Stimulus characteristics were also varied: pure tones and clicks were both used as the stimuli to be localized.

While two statistically significant findings of facilitation occurred, the bulk of the evidence led to the conclusion that the facilitation of auditory localization was not demonstrated in this series of experiments.

These results were discussed in terms of common explanations of intersensory effects. The possibility that the alerting of activating function of accessory stimulation could be the basis for the effect was raised. It was hypothesized that habituation of the alerting response might be responsible for the inconsistent pattern of results found in the literature. Suggestions for future research were noted.