Multiple P3s to emotional stimuli and their theoretical significance.

Event-related potentials (ERPs) were recorded to both predictive (consonant-vowel-consonant) and feedback (picture) stimuli as subjects learned associations between these stimuli. Tbe eonsonantvowel-consonants (CVCs) were selected for lack of emotional content while the pictures (PICs) varied in emotional value (Learning Group; N = 20). A second group of subjects was exposed to the same CVC-PIC stimuli but was required only to count tbe number of different CVCs and PICs (Counting Group; N = 20). A principal components analysis witb varimax rotation was performed on ERPs to PICs and revealed multiple late positive components (P3 and F4) and a slow positive wave (SPW). In both groups, the P3 and P4 factors varied with the emotional value of the stimuli. Tbe learning group bad a larger SPW tban the counting group, and disconiirmed predictions elicited larger P4s tban confirmed predictions. For C\C stimuli, only P4 increased as subjects learned CVC-PIC" relationships. From tbe similar scalp and temporal distributions of P3 and P4, as well as tbeir functional similarity, it was concluded tbat tbese two factors reflect the same neural process whicb is activated by the emotional value of stimuli. One possible function of tbis process is suggested. DESCRIPTORS: Event-related potentials, P3, P4, Slow wave. Emotion, Utility, Learning. The concept of utility, the personal subjective It appears that all value must originate from an value of a sttmulus, was proposed as a major factor inherent emotional structure which: 1) defines cerdetermining P3 amplitude in order to reconcile the tain stimuli as desirable or undestrable for biologeffects of "task relevance" with the effects of maical survival, and 2) provides a cognitive mechanipulating tbe "monetary value" of a stimulus nism for elaborating this basic emotional structure. (Johnston, 1979). It is clear that both monetary valFrom this perspective, all value is emotive in naue and task relevance are learned stimulus attriture. Begleiter, Porjesz, Chou, and Aunon (1983) butes. In a subsequent study, Johnston and Hoihave discussed this issue, and concluded that "the comb (1980) examined how the P3 elicited by a cognitive processes for determining the 'meaning" neutral stimulus (SI) could come to reflect the value or 'significance' of stimuli must of necessity possess of a subsequent high utility event (S2) as subjects a fundamental and critical emotive aspect" (p. 100). learned the relationship between SI and S2 in a The idea that emotional value is a major deterpaired associate learning task. The question reminant of P3 amplitude is supported by Simons' mains, however, as to the nature of the original (1982) study which showed reduced P3 amplitude value system from which learned values are dein anhedonic subjects, compared with normals, to rived. stimuli which were predictive of high interest slides. The present experiment is an attempt to systematically manipulate the emotional value of stimuli Address requests for reprints to: Dr. Victor S. lohnand examine how this is reflected in P3 amplitude, ston. Department of Psychology. Box 3452. New Mexico Furthermore, the study is designed to determine if State University. Las Cruces, New Mexico 88003. ERPs to neutral stimuli change as subjects learn the 684 November, 1986 Multiple P3s To Emotional Stimuli 685 relationship between these stimuli and ones with high emotional value.