Abstract
Purpose: Pursuit latency is shortest with high contrast, first order stimuli. Low contrast and third order stimuli show longer latency due to increased processing and/or longer pathways through different areas. Here we looked at a comparison of eye and hand movement latencies to see if both changed together with task type. Method: Stimuli were squares of 1 and 2 degrees on a side, defined by high contrast edges, low contrast edges, or by orientation differences in dynamic noise. One square moved in a random walk, the other moved under joystick control as the subject tried to keep them concentric. Left eyes were tracked by a dPi tracker. Eye and hand velocities were cross correlated with target velocity to extract response latencies. Results: The average latency of ocular pursuit for three subjects was 90 msec for high contrast, 111 msec for low contrast, and 127 msec for orientation defined targets. Hand responses were about 90 msec slower than eye responses, regardless of stimulus type. Conclusions: Given the multiplicity of visual areas, it is reasonable to expect latency to change with stimulus type. The fact that eye and hand latencies change identically suggests they are driven by the same visual processes.