This thesis examined the event-related brain potentials recorded while subjects perform a continuous involvement perceptual-motor task. It was found that potentials associated with psychological processes of anticipation and selective attention could be reliably measured. A post-stimulus negative shift observed in response to attended stimuli was found to be composed of two types of electrocortical activity. The first and earliest to appear was sensitive to the difference between channels (i.e. ears) carrying relevant and irrelevant auditory information. The second was sensitive to the direction in which subjects oriented their attention during the task. Between 200 msec and 300 msec after stimulus onset, these two activities or processes interacted such that the electrocortical effect of selective attention became largest in the cerebral hemisphere contralateral to the direction of orientation. Predicted relationships between brain potentials and task performance on a trial-to-trial basis were not found. The results are discussed in terms of the current understanding of the electrophysiology of human attention.Arts, Faculty ofPsychology, Department ofGraduat
