Rapid Audiovisual Integration Guides Predictive Actions.

Natural movements, such as catching a ball or capturing prey, typically involve multiple senses. Yet, laboratory studies on human movements commonly focus solely on vision and ignore sound. Here, we ask how visual and auditory signals are integrated to guide interceptive movements. Human 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. Movement end points revealed systematic overestimation of target speed when the ball launch was paired with a loud versus a quiet sound, although sound was never informative. This effect was modulated by the availability of visual information; sounds biased interception when the visual presentation duration of the ball was short. Amplitude of the first catch-up saccade, occurring ∼125 ms after target launch, revealed early integration of audiovisual information for trajectory estimation. This sound-induced bias was reversed during later predictive saccades when more visual information was available. Our findings suggest that auditory and visual signals are integrated to guide interception and that this integration process must occur early at a neural site that receives auditory and visual signals within an ultrashort time span.