The effect of attentional effort on visual evoked potential N1 latency.

The latency of the visual evoked potential N1 component evoked by nontarget stimuli increases with an increased attention to nontarget stimuli. The latency increase seems related to a general effort at processing, rather than any early filtering. This phenomenon is illustrated in one study of hyperactive children and another of normal young adults. The literature of this phenomenon is reviewed, and various explanations are considered. It does not appear to be a result of a slow negative wave, but rather a genuine effect of one aspect of attention on N1.