Abstract
Saccade related brain potentials were examined during visual orientation and discrimination of geometric figures. Eight graduate students participated in the experiment. Three geometoric figures were used : a circle, a square, and an eight-sided figure. Stimuli were presented at locations 15°in visual angle apart (left/right) from the center of the CRT screen. Subjects were asked to fixate one of two locations where one of the three figures was presented. EEGs were recorded from 8 locations on the scalp under the following conditions : (1) NON-TARGET condition; subjects were asked to follow the presented figure. (2) TARGET condition; subjects were asked to follow and detect the presented figure, and to press the button when the figure was a circle. EEGs were averaged before and after the offset of saccade. Amplitude of the lambda response in the right occiput (O2) was larger than that in the left occiput (O1). In TARGET condition, both a circle and an eight-sided figure evoked a negative component 200ms after the saccade offset. A positive component appeared at about 300ms after the saccade offset and the latency of that component evoked by an eight-sided figure was longer than that evoked by a square. These results suggested that figure discrimination process may be reflected partly in the saccade related brain potentials.
