How do target predictability and precueing affect the production of express saccades in monkeys?


: Dr Peter H. Schiller, 400 Main Street, E25-634, Cambridge, MA 02139, USA.


The extent to which target predictability and precueing affect express saccade generation was determined in Rhesus monkeys. Target predictability, as manipulated by the probability with which targets appeared at various locations, had a strong influence on express saccade generation. Pre-cueing the location of the appearance of an impending single target with an identical stimulus was effective in increasing express saccade generation when there was a gap of 50–150 ms between fixation spot termination and target onset. However, precueing was not effective when the gap time was set to 0 ms in the single target task, when several simultaneous targets appeared requiring a visual discrimination to be made using an oddity task, or when the precue was not identical to the target. These findings indicate that express saccades are facilitated by a restricted set of conditions that increase the predictability of target location and identity.