SPLTRAK Abstract Submission
Fear, Fright, Flight: Can Human Body Odors Convey Emotion Intensity?
Jasper H.B. de Groot1,2, Peter A. Kirk1, Jay A. Gottfried1,3
1Department of Neurology, University of Pennsylvania, Philadelphia, PA, United States
2Department of Social, Health, & Organizational Psychology, Utrecht, Netherlands
3Department of Psychology, University of Pennsylvania, Philadelphia, PA, United States

Humans can implicitly inherit emotional states (e.g., fear) based on another person’s body odor (BO). Whereas prior research has treated emotions as categorical constructs, here we focus on another important aspect of emotions – the degree of emotional intensity – and whether this information can be communicated chemically. Here we tested the hypothesis that there is a dose-response relation between experienced fear intensity by a sender (low, medium, high) and experienced fear intensity by a receiver (a lower criterion to identify fear across a spectrum of faces between fear, disgust). Method: Study 1 entailed collecting BOs from 36 male senders induced under either fearful (horror clips) or calm (control) conditions. Using Partial Least Squared-Discriminant Analysis, senders were then successfully subdivided into 3 fear intensity groups (low, medium, high) based on their regression-weighted subjective ratings and physiological responses. The goal of the subsequent receiver Study was to dissect components of fear odor processing at the behavioral, physiological, and neural levels, by combining fMRI, olfactory psychophysics, and pattern-based imaging analysis. In a double-blind within-subjects design, 31 female receivers were exposed to the 3 levels of fear BO and control BO on separate trials during fMRI scanning, while rating faces morphed between fear and disgust. Results: All BOs (fear, neutral) were indistinguishable, iso-intense, and iso-pleasant; yet, all fear odors (low, medium, high) significantly reduced receivers’ subjective criterion to identify fear in ambiguous faces, F(1, 26) = 13.44, = .001; and FOs induced longer sniffs (= .039) (vigilance). The neural data (to be analyzed) will give further insights into the functional organization of social odor coding in the human brain.