Abstract
At rest, the perception of brief flashes is biased by co-occurring brief beeps (i.e., audio-visual illusion: Shams et al. 2000; Andersen et al. 2004). However, during fast and accurate goal-directed movements, susceptibility to audio-induced visual illusions is lessened, specifically during the high velocity portions of the trajectory (Tremblay & Nguyen, 2010). One explanation for such findings is the sensory gating hypothesis (e.g., Chapman & Beauchamp, 2006), which is thought to primarily occur just before and early during a movement. Employing vision-induced auditory illusions, this study tested if the modulation of the audio-visual illusion could be explained by the gating of auditory information. Thirteen participants performed rapid and accurate upper-limb movements towards a visual target. At rest and during reaching movements, 0, 1 or 2 flashes were presented simultaneously with 1 or 2 beeps. During the movement trials, these audio-visual stimuli were presented at 0, 200, and 400 ms relative to movement onset. Participants were asked to report the number of beeps heard after each trial. An ANOVA contrasted the perceived number of beeps using a 4 presentation time (rest, 0, 200, 400 ms) by 3 flash (0, 1, 2) by 2 beep (1, 2) design. On average, participants perceived fewer beeps when 1 beep was presented in the 0 ms condition, compared to the other presentation times. Further, the average number of perceived beeps was influenced by the number of flashes presented in both the 0 ms and 200 ms conditions. These results suggest that auditory information processing is suppressed as one initiates an action, while the influence of action on visual information processing takes place over a longer period of time. We conclude that auditory gating alone is not sufficient to explain modulations in the perception of the audio-visual illusion during goal-directed action.
Meeting abstract presented at VSS 2014