Oculomotor capture by abrupt onsets reveals concurrent programming of voluntary and involuntary saccades

In several recent experiments we have found that the eyes are often capture d by the appearance of a sudden onset in a display, even though subjects in tend to move their eyes elsewhere. Very brief fixations are made on the abr upt onset before the eyes complete their intended movement to the previousl y defined target. These results indicate concurrent programming of a volunt ary saccade to the defined saccade target and an involuntary saccade to the sudden onset. This is inconsistent with the idea that a single salience ma p determines the location of a saccade in a winner-take-all fashion. Other results indicate that subjects attend to more than one location in a displa y during saccade preparation, contrary to the claim that covert attentional scanning plays no role in saccade generation.