Improvement in direction discrimination: no role for eye movements.

Abstract

Practice improves observers’ ability to discriminate between highly similar directions of motion. In an effort to clarify the basis for this improvement, we recorded an observer’s eye movements while he made direction discriminations. We found that the observer did not need to track the moving target in order to learn the discrimination. Both at the beginning and at the end of training the observer’s eye movements more closely resembled movements made while fixating a stationary target, and did not at all resemble movements made while intentionally tracking the stimulus. These results suggest that the learned discrimination of the direction of moving targets is perceptual in nature and does not depend on the learning of a sensorimotor response.