Multisensory Enhancement in Auditory and Visual Noise in Adults

Although, multisensory signals often occur in noise in natural settings, few studies have compared the effect of noise on multisensory enhancement over unisensory stimulation. Twenty-two young adults completed an audiovisual discrimination task in which targets were presented in quiet and in auditory, visual, and audiovisual noise conditions. Stimuli comprised auditory, visual, and audiovisual domestic animal exemplars. Motor reaction times (MRTs) and error rates (< 7% for all stimulus types) were recorded. Multisensory enhancement was evident in all noise conditions. MRTs to audiovisual targets were slowed in visual and audiovisual noise compared to quiet. Percentage gain in audiovisual over unisensory MRTs was higher in visual and audiovisual noise than in auditory noise alone. However, there were fewer violations of the predicted inequality in the race model in audiovisual (.15–.25 probabilities) compared to visual (.15–.65 probabilities) and auditory noise and quiet (both .05–.65 probabilities). Increased variability could not explain reduced coactivation in audiovisual noise, suggesting that targets are processed differently in multisensory than unisensory noise or quiet. The multisensory advantage in visual and audiovisual noise can be explained by a greater increase in reaction times to unisensory than audiovisual targets. The findings of the study suggest an increasing interaction between multisensory integration and crossmodal attention in noise with a high visuoperceptual load