Intraindividual Variability Matters for the Correspondence Between Subjective Arousal, Valence, and Physiological...

Affective experiences are inevitably accompanied by physiological changes. However, it is still a matter of intense debate whether events evoking similar affective experiences produce comparable physiological responses (fingerprint hypothesis) or variation is the norm within individuals (populations hypothesis). We reanalyzed data from two independent samples (N = 695; N = 64), using representational similarity analysis (RSA) to examine the trial-by-trial similarity patterns of subjective experience of valence and arousal and affect-related physiological measures (skin conductance [SCR] and startle blink responses) and their modulation by physiological intraindividual variability. Across physiological measures and tasks (passive picture viewing, passive sound listening, and imagery tasks), we observed that disregarding versus considering intraindividual variability when constructing psychophysiological response patterns yielded different associations with affective models, aligning with the fingerprint hypothesis and the populations hypotheses of affect, respectively. More importantly, follow-up analysis revealed that considering intraindividual variability yields a better representation of the SCR and startle patterns across individuals and tasks. Our results demonstrated that similar affective experiences are rather reflected by distinct physiological responses and emphasized the importance of considering intraindividual variability in future studies to better understand how physiological changes contribute to conscious affective experiences in humans.