Enhanced visual dominance in far space.

The Colavita effect refers to the phenomenon that people do not respond to an auditory stimulus in most cases when a visual stimulus is simultaneously presented. Although the Colavita effect remains robust irrespective of many factors, little is known concerning how the visual dominance varies as a function of the depth of sensory inputs. In the present study, visual and auditory stimuli were presented either in the same (in Experiment 1) or in the different spatial distances (in Experiment 2). Participants were asked to make speeded responses to unimodal auditory, unimodal visual, or bimodal audiovisual stimuli. In the incorrectly responded bimodal trials, the error trials in which responses were made only to the visual component were compared with the trials in which responses were made only to the auditory component. In the correctly responded bimodal trials, the trials in which participants responded first to the visual component were compared with the trials in which participants responded first to the auditory component. Analysis on the incorrect and correct bimodal trials both indicated significant visual dominance effects. More importantly, the size of the visual dominance effect was significantly enhanced as long as the visual stimuli were presented in far space irrespective of whether the auditory stimuli were presented in near or far space. Our results thus, for the first time, revealed that the visual dominance effect changed along the depth dimension of space. Taken together, the present results shed lights on how the allocation of attentional resources along the depth dimension of space biases the process of multisensory competition.