Pursuit eye movements to second-order motion targets.
We studied smooth-pursuit eye movements elicited by first- and second-order motion stimuli. Stimuli were random dot fields whose contrast was modulated by a Gaussian window with a space constant of 0.5 degrees. For the first-order stimuli, the random dots simply moved across the screen at the same speed as the window; for the second-order stimuli the window moved across stationary or randomly flickering dots. Additional stimuli which combined first- and second-order motion cues were used to determine the degree and type of interaction found between the two types of motion stimuli. Measurements were made at slow (1 degrees/s) and moderate (6 degrees/s) target speeds. At a velocity of 1 degrees/s the initiation, transition, and steady-state phases of smooth pursuit in response to second-order motion targets are severely affected when compared with the smooth pursuit of first-order motion targets. At a velocity of 6 degrees/s there is a small but significant deficit in steady-state pursuit of second-order motion targets but not much effect on pursuit initiation.
Hawken
M J
MJ
Center for Neural Science, New York University, New York 10003, USA. mjh@cns.nyu.edu
Gegenfurtner
K R
KR
D015350:Contrast Sensitivity / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D006706:Homeostasis; D006801:Humans; D008027:Light; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011698:Pursuit, Smooth / Q000502:physiology*; D013997:Time Factors