Distractor interference during smooth pursuit eye movements.
When 2 targets for pursuit eye movements move in different directions, the eye velocity follows the vector average (S. G. Lisberger & V. P. Ferrera, 1997). The present study investigates the mechanisms of target selection when observers are instructed to follow a predefined horizontal target and to ignore a moving distractor stimulus. Results show that at 140 ms after distractor onset, horizontal eye velocity is decreased by about 25%. Vertical eye velocity increases or decreases by 1 degrees /s in the direction opposite from the distractor. This deviation varies in size with distractor direction, velocity, and contrast. The effect was present during the initiation and steady-state tracking phase of pursuit but only when the observer had prior information about target motion. Neither vector averaging nor winner-take-all models could predict the response to a moving to-be-ignored distractor during steady-state tracking of a predefined target. The contributions of perceptual mislocalization and spatial attention to the vertical deviation in pursuit are discussed.
Spering
Miriam
M
Justus-Liebig-Universitat Giessen, Allgemeine Psychologie, Giessen, Germany. miriam.spering@psychol.uni-giessen.de
Gegenfurtner
Karl R
KR
Kerzel
Dirk
D
D000328:Adult; D001288:Attention; D005133:Eye Movements / Q000502:physiology*; D005403:Fixation, Ocular; D006801:Humans; D007266:Inhibition, Psychological; D010470:Perceptual Masking