Attentional distraction of CNV depending on the spatial focus.

To investigate the distraction of spatial attention to the task-irrelevant visual stimuli, contingent negative variation (CNV) was measured by using a forewarned reaction time task in 20 healthy subjects. The lasting emission of light, irrelevant to the CNV task, at each perimetric angle of 15°, 30° or 45° to the fixated point was presented to the subjects. The amplitude of early CNV was small only under the light-emission at the angle of 30°. Our results indicate that attention is distracted even by the lasting, task-irrelevant stimuli and that distraction is dependent on the focusing function of attention.