Modification of eye movements by instantaneous changes in the velocity of visual targets

The question of how information concerning the motion of targets becomes manifested in eye movements was answered in the following way. Monkeys, previously taught to track visual targets, were exposed to targets whose velocity was instantaneously changed at varying intervals after the onset of target movement. Both saccadic and smooth pursuit eye movements could be altered by changes in target velocity introduced during the first 90 msec of target movement. A change in the velocity of the target could affect the size of a saccade occurring only 50 msec later. Saccadic eye movements occurred with intersaccadic intervals as short as 20 msec. These results indicate that both saccadic and smooth pursuit eye movements are based on continuously processed information.