On the Mechanisms of Audio-Visual Integration for Manual Interception

Natural interception actions such as catching a ball require accurate motion prediction and typically involve multiple senses. Laboratory interception studies focus on vision and commonly ignore sound. Here we ask how visual and auditory signals are integrated to guide interception. Observers tracked the brief launch of a simulated baseball randomly paired with batting sounds of varying intensities and made a quick pointing movement at the ball. Interception endpoints revealed systematic overestimation of target speed when ball launch was paired with a loud versus a quiet sound, even though sound was never informative. We applied a Bayesian observer model showing that audio-visual integration, strongest at the shortest presentation duration, depended on visual certainty. Continuous eye movements uncovered that sound influenced visual speed estimates within 125 ms of ball launch. Our findings suggest that auditory and visual signals are rapidly and optimally weighed to guide interception.