Cross-modal interactions in auditory and visual discrimination.

Three experiments examined auditory-visual interactions using two sensory discrimination paradigms. Experiments 1 and 2 used a one-interval confidence-rating procedure and found modest effects of concurrent visual stimulation on auditory pitch and loudness discrimination, but little effect of auditory stimulation on visual brightness discrimination. The cross-modal interactions could have either a sensory or decisional basis. Experiment 3 used a two-interval same-different procedure and found no effect of visual stimulation on auditory sensitivity in pitch discrimination, and very little effect of auditory stimulation on visual sensitivity in brightness discrimination. Although the ensemble of results could be explained by sensory facilitation and/or inhibition that varies with the behavioral task, the pattern of these and related findings suggests instead that the cross-modal interactions result primarily from relatively late decisional processes (e.g. shifts in response criterion or 'bias').