In this paradigm, two stimuli are presented randomly, with one occurring infrequently. The subjects were asked to discriminate target (20%) from non-target or standard stimuli (frequent 80%). In the present experiment, target stimuli were represented by a sound (4000 Hz 50 msec.) or bitmap and non-target, by a sound (1500 Hz 50 msec.) or bitmap. Subjects were instructed to respond to the target stimulus by pressing a mouse button. The button was used to measure individuals' reaction time at each trial.
P50