Distribution of OKN SP velocities.

<p><i>Center panel</i>: Distribution of gaze velocities in two dimensions. Level curves enclose 50% of all OKN SP velocity measurements in the different conditions. Dots are individual participants’ mode velocities. The Control and “normal” data are clustered in the bottom left quadrant–while the the “tp” data are clustered at the zero value (except for participant 9). Dashed line indicates predicted pursuit for visually tracking a waypoint (-1/2 average yaw rate). <i>Top and left panels</i>: Horizontal and vertical gaze velocity density estimates in the different conditions.