Oxyopia Abstract

April 18, 2008
Friday, 4:00 PM
CANCELLED
489 Minor Hall

J. Douglas Crawford, PhD
Professor, Psychology, Biology and Kinesiology & Health Science, York University, Toronto
Host: Martin Banks

Title

Spatial Updating for Perception and Motor Control

Abstract

We make rapid eye movements called saccades about 3-4 times per second, and each one changes the spatial relationship between the retinal and the world. This poses a computational problem both for motor control (i.e., aiming movements toward objects that we viewed from a previous eye position) and for perception (i.e., for synthesizing visual information that was gathered from different eye positions. More is known about how this 'spatial updating' problem is solved for motor control, so this is where we will begin. After presenting various theoretical models, I will show fMRI evidence which suggests that parietal cortex updates visual space in eye-centered coordinates for reaching movements and saccades. Then we will consider various psychophysical / computational aspects of 'trans-saccadic integration', the process of integrating visual features from different visual fixations. Finally, I will present new evidence from TMS (trans-cranial magnetic stimulation) experiments which suggest that perceptual integration taps into the same parietal updating mechanisms that have been demonstrated previously in motor control.

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