Audiovisual asynchrony modulates the Colavita visual dominance effect.

Participants presented with unimodal auditory, unimodal visual, or bimodal audiovisual stimuli in a speeded discrimination task, fail to respond to the auditory component of bimodal targets significantly more often than they fail to respond to the visual component. We explored the influence of temporal factors on this phenomenon, known as the Colavita visual dominance effect. Participants performed a temporal order judgment (TOJ) task followed by the Colavita task. The stimulus onset asynchrony (SOA) between the auditory and visual components of the bimodal targets was varied and the results showed that the point at which the Colavita effect disappeared was correlated with the point at which participants started to reliably perceive the auditory stimulus as coming first. Furthermore, no Colavita effect was observed at those SOAs where the participants always perceived the visual stimulus as having come first. These results are explained in terms of the unity effect; that is, the Colavita visual dominance effect occurs within the temporal window in which participants bind auditory and visual stimuli into a single multisensory perceptual event. However, within this window, the Colavita effect is larger when the visual (rather than the auditory) stimulus is presented first.