During oddball tasks, control subjects manifest enhanced P3 components and evoked theta, delta, and gamma oscillations when processing the target stimulus but not when processing a nontarget or novel stimulus. Alcoholics, however, manifest less electrophysiological differentiation among the three stimulus categories. Topographic maps of P3s and these EROs during target processing indicate that not only do alcoholics manifest weaker sources, they have less topographically distinct spatial–temporal patterns. This less differentiated mode of responding during various tasks indicates that alcoholics are less proficient at processes which involve comparing a new stimulus to a template, suggesting alcoholics have attention and memory deficits. Alcoholics seem less able to efficiently use available information (e.g., a template in working memory) to respond differentially to incoming stimuli (targets, nontargets); hence each incoming stimulus must be evaluated anew. This more global mode of responding in alcoholics regardless of stimulus and task requirements indicates a basic diminution of differential inhibition. In healthy people, familiar stimuli are processed with less neuronal activity than unfamiliar stimuli. Evidence from monkey studies indicates that repeated stimuli elicit less neuronal firing than novel
