Effects of audiovisual motion coherence on multisensory processing

Abstract

Frequently, the presentation of stimuli from two sensory modalities results in behavioral benefits, including improvements in the detection and accuracy of responses and a speeding of response times. Although these benefits have been shown using both simple and complex multisensory stimulus pairs, they have not been extended to the domain of motion coherence. We developed auditory motion stimuli to parallel the varying motion coherence levels of random dot kinematograms (RDKs) by simulating the motion of a broadband noise within a static uncorrelated broadband noise. Using these auditory stimuli and visual RDKs at varying levels of motion coherence, we tested the behavioral gains associated with multisensory pairs. Both the accuracy and timing of responses to unisensory (i.e., auditory alone, visual alone) stimuli versus multisensory stimuli were assessed at four different levels of motion coherence: 10%, each individual’s threshold, average threshold for our population, 70%. In addition, responses were assessed for congruently or incongruently moving stimuli (i.e., the auditory and visual motion either moved in the same direction or opposite directions). We found that maximum gains in multisensory performance (e.g., greater response accuracy and more race-model violations) were seen at threshold levels of motion coherence; levels at which the unisensory cues have maximum ambiguity. This study further reinforces the utility of multisensory integration for weakly effective stimuli, and expands the multisensory toolbox to include motion stimuli used in the examination of sensory processing in clinical populations including autism and schizophrenia.