P300 and probability: comparison of oddball and single-stimulus paradigms.

The P300 event-related brain potential (ERP) was elicited with auditory stimuli in two different tasks. The oddball paradigm presented both target and standard stimuli; the single-stimulus paradigm presented a target but no standard tone stimulus, with the inter-target interval the same as that for the oddball condition. Target stimulus probability was manipulated in the oddball task in different conditions (0.10, 0.30, 0.50, 0.70, 0.90). The single-stimulus paradigm employed the same procedures such that the inter-target interval was identical as that for the oddball condition across changes in probability. P300 amplitude and latency were similar for both the oddball and single-stimulus procedures across probability levels. Correlations between the P300 values from each task mimicked those from test-retest comparisons for the oddball paradigm. The findings suggest that P300 from the single-stimulus paradigm responds to target stimulus probability in the same fashion as the traditional oddball. The implications of the single-stimulus technique are discussed in terms of applied contexts that require very simple ERP task conditions.