Voluntary action decreases spatial perception in central and peripheral vision


The spatial perception of a visual stimulus is optimal at the fovea and diminishes with increasing eccentricity (Brown et al., 2005). As well, visual perception has also been shown to be modulated during a voluntary movement. For example, temporal visual events are less susceptible to accompanying auditory cues during movements (Tremblay and Nguyen, 2010) while spatial cues are more poorly perceived at peak-limb velocity (Hajj et al., 2019). However, visual stimuli in these studies were presented below and at the fovea, respectively, which may explain the discrepant results for temporal vs. spatial perception. The purpose of this study was to investigate how visual spatial processing differs in peripheral vs. central vision at peak-limb velocity. Participants (n=12) performed an inspection time (IT) task whereby they identified the longest side of a briefly presented (25-150 ms) asymmetrical pi figure. In the no-movement condition, the IT task occurred in central (1deg) and peripheral (15deg) vision while participants grasped a manipulandum. In the movement condition, the IT stimulus appeared at and below the foveated target at peak-limb velocity of a rapid 30deg elbow extension to a target. While IT task performance was significantly poorer in the peripheral field, visual spatial processing was further diminished at peak velocity in both peripheral and central vision. These findings indicate that changes in temporal visual event perception during voluntary action (Tremblay and Nguyen, 2010) are accompanied by decreased spatial perception of visual stimuli at peak-limb velocity both at the fovea and at 15deg of visual eccentricity.

Acknowledgments: University of Toronto, Natural Sciences and Engineering Research Council of Canada (NSERC)