Electro‐cortical and Cardiac Rate Correlates of Psychophysical Judgment

Nine undergraduate volunteers participated in a frequency discrimination task. They were asked to rank five different pure tones, presented individually, and report their judgment several seconds after each tone terminated. Tones generally ranked correctly in frequency yielded larger fast‐cortical potential* and evoked heart rate respoases. Stimuli which occasioned frequent errors prompted a specific, negative, slow cortical wave, which could be distinguished both from eye movement artifact, and the slow wave changes associated with orienting and anticipation. The physiological data were analyzed in ternvs ot'two conceptions of the cognitive processing involved in psychophysical judgments.