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Autonomic specificity of basic emotions: Evidence from pattern classification and cluster analysis

Autonomic nervous system (ANS) specificity of emotion remains controversial in contemporary emotion research, and has received mixed support over decades of investigation. This study was designed to replicate and extend psychophysiological research, which has used multivariate pattern classification analysis (PCA) in support of ANS specificity. Forty-nine undergraduates (27 women) listened to emotion-inducing music and viewed affective films while a montage of ANS variables, including heart rate variability indices, peripheral vascular activity, systolic time intervals, and electrodermal activity, were recorded. Evidence for ANS discrimination of emotion was found via PCA with 44.6% of overall observations correctly classified into the predicted emotion conditions, using ANS variables (z=16.05, p<.001). Cluster analysis of these data indicated a lack of distinct clusters, which suggests that ANS responses to the stimuli were nomothetic and stimulus-specific rather than idiosyncratic and individual-specific. Collectively these results further confirm and extend support for the notion that basic emotions have distinct ANS signatures.

Redundancy analysis of autonomic and self-reported, responses to induced emotions

The issue of concordance among the elements of emotional states has been prominent in the literature since Lang (1968) explored the topic in relation to therapy for anxiety. Since that time, a consensus has emerged that concordance among these components is relatively low. To address this issue, redundancy analysis, a technique for examining directional relationships between two sets of multivariate data, was applied to data from a previously published study (Stephens, Christie, & Friedman, 2010). Subjects in this study listened to emotion-inducing music and viewed affective films while a montage of autonomic variables, as well as self-reported affective responses, were recorded. Results indicated that approximately 27–28% of the variance in self-reported affect could be explained by autonomic variables, and vice-versa. When all of the constraints of this emotion research paradigm are considered, these levels of explained variance indicate substantial coherence between feelings and physiology during the emotion inductions. These results are considered vis-à-vis the low levels of coherence that have often been reported in the literature.