This study investigates a negative component (N220) of visual evoked potential (VEP) which increases as certain cognitive processes are activated. Nine experimental conditions were designed by combining three stimulus and three task conditions. Letters were used as verbal stimuli, matrix patterns were used as nonverbal stimuli, and white light was used as a non-structural stimulus. Non-response, comparison and counting tasks were performed. Subjects were eight 8- and 9-year-old children who had normal visual acuity and average intelligence. All were right-handed and were confirmed to have neither EEG dysrhythmia nor neurological abnormality. Stimuli were presented for approximately 500 - 800 msec on a viewing screen placed 80 cm in front of the subjects. The VEP was recorded in the left parietal, the right parietal and the mid-occipital regions (by the International 10 - 20 method) using Ag - AgCl electrodes referenced to the left earlobe. Cortical activity was amplified by Nihon Kohden ME - 135D Polygraph and recorded on FM magnetic tape for later analysis. Results indicate that N220 increases under conditions of response task combined with structured stimuli. The increase is especially clear when same-different judgments are elicited with verbal stimuli. A clear fluctuation in the sensory non-specific parietal region is noted when compared to the sensory specific occipital region, indicating that N220 is not entirely due to physical characteristics of the stimuli. Rather, N220 reflects the endogenous process necessary to perform the cognitive tasks. (Author/RH)