An Exploration of the Factors that Modulate Sensory Dominance.

Abstract

Investigations of multisensory integration have demonstrated that under certain conditions, one modality is more likely to show dominance over the other, with strong evidence over the past few decades suggesting that the visual modality is more dominant. However, this visual prepotency effect can be reversed to show auditory dominance in certain tasks. The experimentation conducted within investigated two stimulus characteristics that have been hypothesized to potentially modulate sensory dominance using an oddball detection paradigm. It was hypothesized that when manipulating stimulus transience (by changing the relative duration of either the auditory or visual stimulus in a bimodal stimulus stream), participants would show dominance for the modality with the shorter duration, as theoretically attention would be drawn to the more transient modality. Participants showed auditory dominance in the 1-button condition irrespective of manipulation to duration. In the 3-button condition participants showed auditory dominance when looking at their response times, but also simultaneously demonstrated visual dominance when using a more traditional measure of sensory dominance (i.e., making a higher proportion of visually based errors to bimodal trials). Furthermore duration did not modulate these errors. The second experiment addressed the hypothesis that a stimulus that is presented earlier will be processed first and therefore contribute to sensory dominance. Stimulus order was manipulated such that the visual or auditory stimulus was presented prior to one another. It was hypothesized that dominance would be observed for the stimulus (auditory or visual) that occurred first. Participants, in the 1-button and 3-button conditions, were more likely to show auditory dominance with simultaneous presentations, and under all conditions where the auditory stimulus preceded the visual stimulus, however auditory dominance was eliminated when the visual stimulus occurred slightly before the auditory stimulus, only demonstrating visual dominance when the visual stimulus preceded the auditory stimulus by 200 ms. Errors in the 3-button task provided evidence for visual dominance which was modulated when presenting auditory stimuli prior to visual stimuli. Overall these results affirm that auditory dominance effects are more pronounced early in processing, whereas visual dominance effects are more pronounced later in processing. Theoretical implications of these results are discussed.