Neuroelectric aspects of information-processing by the brain

Abstract

Auditory, visual, and tactile evoked responses were recorded in a series of experiments in which selective attention and information-processing demands were varied. The technique of “shadowing” was employed, requiring subjects to reproduce, with minimized phase-lag, either auditory or tactile messages. The accuracy and the lag-time of the subject's “shadowing” responses serve as measures both of attentiveness and of the processing demands of the task. This paradigm allows direct assessments of single-channel vs multiple-channel hypotheses of human information-processing. It further permits experimental control of the subject's attention to an extent generally lacking in studies of the relationship between brain responses and attention. The present findings indicate that those current models of human information-processing which impose rigid constraints on the system must be qualified; that both single-channel and multiple-channel features can be disclosed in brain-response data; that systematic relationships obtain between, on the one hand, the information-processing demands of a task and, on the other, the amplitude and variance of cortical responses to otherwise extraneous stimuli presented as the subject performs the task. Theoretical implications of the findings are explored.