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Audiovisual temporal synchrony modulates fast sensorimotor transformation in smooth pursuit eye movements

Poster Session A - Saturday, March 7, 3:00 – 5:00 pm, Fairview/Kitsilano Ballrooms

Hiu Mei Chow¹ (dorischm@gmail.com), Gavin Woodward¹, Beatrix Culligan¹; ¹St. Thomas University, Fredericton, Canada

Being able to respond to novel events can be adaptive, such as quickly stepping on the brakes to avoid colliding with an unexpected cyclist while driving. Interestingly, such adaptive orienting can also be reflected as a temporary inhibition of eye movements. For instance, in pursuit inhibition, as an observer smoothly tracks a moving object, their tracking velocity slows shortly after a transient stimulus is presented. Although pursuit inhibition to a multisensory transient has been shown to be more robust, whether it adheres to established rules of multisensory orienting, such as temporal synchrony, remains poorly understood. Here, we tested whether pursuit inhibition is stronger when the multisensory transient is presented simultaneously than asynchronously. Twenty-eight participants were instructed to track a slowly moving visual target on the screen while visual (a pair of Gabor strips) and/or auditory (white noise) transients occurred at unexpected times. Their eye positions were recorded using a video-based eye tracker. Results from most participants show a reliable drop in pursuit velocity around 100 ms following transient onset, which was stronger with an audiovisual transient than with visual-only or audio-only transients, replicating previous effects. This inhibitory effect seems relatively automatic, as adding a secondary task (pressing a button when a transient was presented) did not affect it. Finally, pursuit inhibition was stronger when audiovisual transients were presented simultaneously than when presented with a 150-ms lag. Our findings support the notion that pursuit inhibition is sensitive in revealing how the brain performs rapid sensorimotor transformations in a multisensory context.

Topic Area: PERCEPTION & ACTION: Multisensory