Direction and extent of perceived motion smear during pursuit eye movement.

Smooth pursuit eye movements superimpose additional motion on the retinal image of untracked visual targets, potentially leading to the perception of motion smear and a distortion of the perceived direction of motion. Previously, we demonstrated an attenuation of perceived motion smear when the untracked target moves in the opposite direction of an ongoing pursuit eye movement. In this study, the extent of perceived motion smear and the direction of perceived smear were compared for a single bright dot that moved in a wide range of directions with respective to horizontal pursuit at 8 deg/s. Comparable data were obtained during fixation as a control. The results indicate that a significant attenuation of perceived motion smear occurs when the dot's motion includes a horizontal component in the opposite direction of eye movement. In contrast, the direction of perceived smear approximates the trajectory of the retinal image motion, during both fixation and pursuit. These results suggest a selective application of extra-retinal signals to compensate specific aspects of visual perception that results from the retinal image motion during smooth pursuit eye movements.