Bisensory Stimulation: Inferring Decision-Related Processes from the P300 Component

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bisensory stimulation & decision making responses, P300 component of evoked response, human Ss

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Conducted 3 experiments with 17 Ss to evaluate the P300 component of the human evoked response as an index of bisensory information processing. On different blocks of trials, Ss were presented with auditory stimuli alone, visual stimuli alone, or audiovisual compounds. In each series there were 2 possible stimuli, one of which was presented less frequently than the other; the Ss' task was to count the infrequent stimuli. In the 1st 2 experiments the information in the 2 modalities was redundant, whereas in the 3rd the modalities provided nonredundant information. With redundant information, the P300 latency indicated bisensory facilitation when the unimodal P300 latencies were similar; when the unimodal latencies were dissimilar, the bisensory P300 occurred at the latency of the earlier unimodal P300. Reaction times (RT) paralleled P300 latency. When the information in the 2 modalities were nonredundant, both P300 amplitude and RT data indicated interference between the 2 modalities, regardless of which modality was task relevant. P300 latency and RT did not covary in this situation. These data suggest that P300 latency and amplitude do reflect bisensory interactions and that the P300 promises to be a valuable tool for assessing brain processes during complex decision making.

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Journal of Experimental Psychology: Human Perception & Performance, v. 3, issue 2, p. 299-315