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A Psychophysiological Mapping of Cognitive Processes.
Final rept. 1 Mar 83-28 Feb 86,
WASHINGTON UNIV ST LOUIS MO BEHAVIOR RESEARCH LAB
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The purpose of these studies was to map the psychophysiological concomitants of cognitive processes. To this end, a modified Sternberg paradigm was used in which the trials were divided into three parts, each beginning with a stimulus. The first, or cue, stimulus informed the subject as to the character of the following memory set. In studies 1 and 2, the cue simply signified the number of letters in the memory set 1,3, or 5 in study 1 2 or 6 in study 2. In study 3, the cue also indicated the character type of the letters either English or Japanese, the latter essentially nonsense patterns for these subjects. The third, or test, letter called for a response as to whether it was a member of the memory set. Physiological responses recorded were ERPs to the above stimuli and to task-irrelevant probe stimuli appearing in the interstimulus intervals, and in Studies 1 and 2, heart rate and blink parameters. In study 1, in the interval preceding the memory set, where attentional demands varied with set size, probe ERP P1-N1 amplitude increased with set size. In study 2, probe stimuli were both visual and auditory so as to assess the specificity of the study 1 ERP effect. The third study examined the differences between left and right hemispheres of the brain in the anticipation of verbal English character and nonverbal Japanese character sets. These findings, coupled with those of study 1, suggest that variation in probe evoked potential amplitudes reflects not only the number, but also the type, of information processing resources demanded by a primary task.
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