The effect of a textured visual field on modality dominance in a ventriloquism situation

Abstract

Despite the often encountered affirmation that vision completely dominates other modalities in intersensory conflict, there are cases where discordant auditorv information affects the localization of a visual signal. Experiment I shows that “auditory capture” occurs with a visual input reduced to a single luminous point in complete darkness, but not with a textured background. The task was to point at a flashing luminous point alternately in the presence of a synchronous sound coming from a source situated 15° to one side (“conflict trials,” designed to measure immediate reaction to conflict) and in its absence (“test trials,” to measure aftereffects). Adaptive immédiate reactions and aftereffects were observed in the dark, but not with a textured background. In Experiment II, on the other hand, “visual capture” of auditory localization was observed at the levels of both measures in the dark and with the textured background. That visual texture affects the degree of auditory capture of vision, but not the degree of visual capture of audition was confirmed at the level of aftereffects in Experiment III, where bisensory monitoring was substituted for pointing during exposure to conflict. The empirical finding eliminates apparent contradictions in the literature on ventriloquism, but cannot itself be explained in terms either of relative accuracy of visual and auditory localization or attentional adjustments.