Self-report and behavioral measures of attitudes and persuasion processes have relied on the bivalent action disposition aroused by the attitude stimulus despite the potential for response distortion. When peripheral somatovisceral measures have been used to investigate communication and attitudes, investigators have traditionally sought to identify responses that were inherently linked to specific affective states. The multiple determinants of somatovisceral responses and the tenuous links between inherent physiological responses and specific affective states have placed strong limits on the usefulness of prior physiological assessments of attitudes. Rather than relying on response dispositions or peripheral physiological responses, the proposed research exploits a more robust relationship between the late positive component of the event-related brain potential (ERP) and categorization processes to study attitude phenomena. In this approach, a subject's attitude serves as the criterion along which stimuli are categorized while ERPs are recorded. In research to date, a late positive potential (LPP) in the ERP has been found to vary as a function of the discrepancy between subjects' attitude toward a target stimulus and their attitude toward the stimuli that preceded the target stimuls. Thus, the more negative (positive) the attitude stimulus embedded within a short sequence of very positive (negative) stimuli, the larger a late positive potential (LPP) amplitude over the centroparietal scalp region (Cacioppo, Crites, Berntson, & Coles, 1993; Cacioppo, Crites, Gardner, & Berntson, 1994); this relationship was found even when overt or verbal responses did not accurately reflect a subject's attitude (Cacioppo et al., 1993; Crites, Cacioppo, Gardner, & Berntson, 1995), and this relationship generalizes across gender, seasons of the year, head sizes, simple phobia status, and experimental (semantic, pictorial) stimuli (Cacioppo et al., 1993, 1994; Crites et al., 1995; Gardner, Cacioppo, Crites , & Berntson, 1995). These results suggest that the LPP amplitude in this paradigm reflects attitude categorization (in contrast to response selection or execution) processes. Finally, the results of five different studies indicate that the LPP amplitude is larger over the right than left hemisphere when a subject's attitude serves as the criterion along which stimuli are categorized; when subjects perform a semantic rather than an evaluative categorization task, in contrast, the LPP amplitude is not lateralized (Cacioppo, Crites, Gardner, & Berntson, under review; Crites, 1994). The primary goal of the proposed research is to use ERPs to test hypotheses regarding affective organization and processing from Cacioppo and Berntson's (1994) model of evaluative space and to contrast these predictions with those made by the circumplex model of affective organization. Self-report and behavioral measures of attitudes and persuasion processes have relied on bipolar measures (e.g., "agree" to "disagree"). These measures are not only susceptible to response distortions (e.g., lying) but they also fail to differentiate individuals who feel neutrally about a stimulus or decision from those who feel ambivalent or conflicted. For instance, individuals who feel neither positive nor negative about abusing drugs or alcohol cannot be differentiated from those who feel both strongly positive and strongly negative about drugs or alcohol (e.g., a remorseful addict). The reasons for the onset or continuation of drug or alcohol abuse, however, differ dramatically between these groups of individuals. In the current research, we continue work on developing a brain-based measure of attitudes and underlying motivational bases that (1) does not require that individuals be willing to report accurately how they feel about persons, objects, or issues; and (2) differentiates not only between the positive and negative motivations underlying attitudes and decisions but also the force (intensity) of each motivational su bstrate. In this approach, a subject's attitude serves as the criterion along which stimuli are categorized while event related brain potentials (ERPs) are recorded. In research to date, a late positive potential (LPP) in the ERP has been found to vary as a function of the discrepancy between subjects' attitude toward a target stimulus and their attitude toward the stimuli that preceded the target stimuls. Thus, the more negative (positive) the attitude stimulus embedded within a short sequence of very positive (negative) stimuli, the larger a late positive potential (LPP) amplitude over the centroparietal scalp region; this relationship is observed even when overt or verbal responses do not accurately reflect a subject's attitude. The primary goal of the research to be conducted over the next two-year period is to use ERPs to contrast competing theoretical models of affective organization and processing to better understand the psychological and cerebral mechanisms underlying productive and counterproductive decisions and behaviors.
