The Dynamics of P300 during Dual-Task Performance

Abstract

This chapter discusses the dynamics of p300 during dual-task performance. When a subject is presented with two stimuli in a Bernoulli sequence and is instructed to count one of the stimuli, a P300 component will be elicited. The amplitude of the P300 will be inversely proportional to the subjective probability of the stimulus. If, however, the same Bernoulli series is presented and the subject is instructed to ignore the stimuli while performing some other task (e.g., solving a crossword puzzle), no P300 is elicited by either of the stimuli, regardless of their probabilities. This observation is consistent with the generally accepted proposition that the amplitude of P300 depends, in part, on the task relevance of the eliciting stimuli. It appears, then, that the subject must in some way “attend” to the stimuli for P300 to be elicited. Attention, however, need not be invested entirely in one task, to the exclusion of all others. Several theories suggest that “attention” should be viewed as a resource of limited supply, various quantities of that can be allocated to different information-processing activities.