The one word task on five colors(1 word/5 colors task) and five word task on five colors(5 words/5 colors task) were created as the stimuli on the stroop task. P300 was measured in order to examine how difficulty of task influenced attention. Sixteen healthy female subjects volunteered for the experiments. When matching color and word names, this became a target stimulus requiring pressing the reaction button. The target stimulus to standard stimulus ratio was 2:8. P300 amplitude was significantly larger in 1 word/5 colors task than in 5 words/5 colors task. P300 latency was significantly shorter in 1 word/5 colors task than in 5 words/5 colors task. The results showed 1 word/5 colors task was difficult, suggesting that P300 amplitude was decreased because of loss of attention.
