Stimulus Onset Modulates Auditory and Visual Dominance

Investigations of multisensory integration have demonstrated that, under certain conditions, one modality is more likely to dominate the other. While the direction of this relationship typically favors the visual modality, the effect can be reversed to show auditory dominance under some conditions. The experiments presented here use an oddball detection paradigm with variable stimulus timings to test the hypothesis that a stimulus that is presented earlier will be processed first and therefore contribute to sensory dominance. Additionally, we compared two measures of sensory dominance (slowdown scores and error rate) to determine whether the type of measure used can affect which modality appears to dominate. When stimuli were presented asynchronously, analysis of slowdown scores and error rates yielded the same result; for both the 1- and 3-button versions of the task, participants were more likely to show auditory dominance when the auditory stimulus preceded the visual stimulus, whereas evidence for visual dominance was observed as the auditory stimulus was delayed. In contrast, for the simultaneous condition, slowdown scores indicated auditory dominance, whereas error rates indicated visual dominance. Overall, these results provide empirical support for the hypothesis that the modality that engages processing first is more likely to show dominance, and suggest that more explicit measures of sensory dominance may favor the visual modality.