CONCURRENT VISUAL TASK EFFECTS ON EVOKED AND EMITTED AUDITORY P300 INADOLESCENTS

Using an oddball stimulus presentation paradigm, the effects of divide d attention on auditory P300s were studied. Auditory attention was eit her divided or focused, depending on the demands placed on subjects du ring the performance of a concomitantly presented visual task. Two typ es of auditory tasks were performed under each of the two auditory att ention conditions. In one, subjects responded to infrequently presente d high pitched tones (oddball stimuli). In the other they responded to the occasional omission of a stimulus in an otherwise rhythmically pr esented chain of stimuli. P300s and reaction times were recorded to bo th the rare tones and the omissions. The Sternberg visual memory task was used to manipulate the subject's auditory attention state. Subject s actively performed the Sternberg task during the divided auditory at tention condition, whereas during the focused attention condition they were not required to respond to the visual stimuli. During focused au ditory attention, evoked auditory P300s were both larger and faster th an their emitted counterparts. During divided attention, auditory P300 s were reduced in amplitude but latency was unaffected. Evoked auditor y P300s showed evidence of containing P300a as well as P300b component s, particularly when attention was shared with the visual task. (C) 19 98 Elsevier Science B.V. All rights reserved.