Abstract
Amplitude characteristics of visual evoked potentials to number (sharp contour) and blurred spot (diffuse contour) stimuli were examined in this experiment. Five male and two female college students were exposed to a series of trials. Each trial consisted of the presentation of seven successive stimuli-a warning stimulus followed by a first triplet of three identical stimuli (stimulus positions 1-3) and a second triplet of another three identical stimuli (positions 4-6). For the numerical stimuli which possessed sharp contours, subjects were required to identify the stimulus pattern by name. For the blurred spot stimuli with diffuse contours, only eye fixation was required of the subjects. Analysis of occipital P260 amplitude revealed significant enhancement at stimulus positions 2 and 3 for the numerical stimuli but not for the blurred spot stimuli. These findings were discussed in terms of the representation process during visual perception.
