Saccadic adaptation shapes visual space in macaques.

Saccadic eye movements are an integral part of many visually guided behaviors. Recent research in humans has shown that processes which control saccades are also involved in establishing perceptual space: A shift in object localization during fixation occurred after saccade amplitudes had been shortened or lengthened by saccadic adaptation. We tested whether similar effects can be established in nonhuman primates. Two trained macaque monkeys localized briefly presented stimuli on a touch screen by indicating the memorized target position with the hand on the screen. The monkeys performed this localization task before and after saccade amplitudes were modified through saccadic adaptation. During localization trials they had to maintain fixation. Successful saccadic adaptation led to a concurrent shift of the touched position on the screen. This mislocalization occurred for both adaptive shortening and lengthening of saccade amplitude. We conclude that saccadic adaptation has the potential to influence localization performance in monkeys, similar to the results found in humans.