The assessment of predictive effects in smooth eye movement control.

Predictive mechanisms in pursuit were studied by requiring subjects to track a moving target which appeared for a brief period (40-320 ms) at regular intervals. With successive presentations the timing of the eye velocity trajectory became progressively more predictive of target appearance, whilst simultaneously increasing in peak velocity. Sudden changes in periodicity or velocity resulted in inappropriate eye movements correlated highly with previous stimulus cycles. The results suggest that prediction involves storage of velocity information and its release under the control of a periodicity estimator.