P300 and allocation of attention in dual-tasks

P300 in dual-tasks has been reported to be distributed reciprocally across the tasks, i.e. larger P300 associated with one task implies smaller P300 associated with the other. In these studies, however, the dual-task stimuli were either presented simultaneously, precluding a direct, within-trial assessment of relative magnitudes of P300, or they were separated by intervals of 1 s or more, thereby minimizing overlap of the ERP epochs, but at the cost of reduced competition for shared processing resources. The present experiment used an inter-stimulus interval of 400 ms between the auditory (tones) and visual (colored LEDs) stimuli that defined the dual-task and found that, when deviant tones elicited a prominent auditory P300, they were followed by a greatly reduced P300 for the deviant LED. The findings were interpreted from viewpoints that considered the effects of neural inhibition versus neural recovery cycles on the amplitude of P300.