P300, STIMULUS-INTENSITY, AND MODALITY

Auditory and visual stimulus intensity levels were manipulated systema tically in separate conditions to assess the influence of these variab les on the P300 event-related brain potential (ERP). Increases in stim ulus intensity produced increases in P300 amplitude and decrases in pe ak latency for both modalities, although the latency effects were stro nger for visual stimulation. Similar, somewhat weaker stimulus intensi ty effects also were observed for the N100, P200, and N200 components. The findings suggest that stimulus intensify contributes to both P300 amplitude and latency measures in important ways and are discussed in relation to the use of ERPs in applied contexts.