On the locus of visual dominance

A series of six experiments explored the dominance of vision over audition reported by Colavita (1974). We first confirmed the existence of visual dominance in a paradigm somewhat different from Colavita's: Mean reaction time (RT) to a light was found to be faster than to a simultaneously presented tone, even though the stimuli were equated in subjective intensity and even though RT to the tone presented alone was faster than to the light presented alone. Additional experiments showed that when subjects did not have to respond to light, tone RT was equal or faster (intersensory facilitation) when a light was present than when it was not. These findings suggest that sensory or perceptual processing of the tone is not affected by the light, i.e., that visual dominance is nonsensory in locus and depends on the relevance of the light stimulus. This interpretation was reinforced by other findings which showed that the degree of visual dominance was sensitive to the probability of light, tone, and light-plus-tone trials and to instructions to attend to a specific modality, but was not sensitive to the intensity of the light.