SOCIAL NEUROSCIENCE, 2011, iFirst, 1–11 The empathic, physiological resonance of stress Tony W. Buchanan 1 , Sara L. Bagley 1 , R. Brent Stansfield 2 , and Stephanie D. Preston 3 1 Department of Psychology, Saint Louis University, St. Louis, MO, USA 2 Department of Medical Education, University of Michigan, Ann Arbor, MI, USA 3 Department of Psychology, University of Michigan, Ann Arbor, MI, USA Physiological resonance between individuals is considered fundamental to the biological capacity for empathy. Observers of pain and distress commonly exhibit increases in reported distress, autonomic arousal, facial mimicry, and overlapping neural activity. An important, unstudied question is whether physiological stress can also res- onate. Physiological stress is operationalized as activation of the hypothalamic pituitary adrenocortical (HPA) and sympatho-adrenomedullary (SAM) axes. People often report an aversive state resulting from the stress of another, but this could be conveyed through resonating arousal or distress, without activating the physiological stress response. Physiological stress is particularly important to examine since it commonly occurs chronically, with known negative effects on health. Salivary cortisol and salivary alpha-amylase (sAA) were measured in both speakers and observers during a modified Trier Social Stress Test (TSST) to assess activation of the HPA and SAM axes (respectively). Cortisol (but not sAA) responses resonated between speakers and observers. The cortisol response of observers increased with trait empathy and was not related to the speaker’s subjective fear or dis- tress. This study provides a novel method for examining physiological resonance, and indicates that we can indeed catch another’s physiological stress, suggesting a specific health risk for those in the social network of stressed individuals. Keywords: Empathy; Contagion; Stress; Cortisol; Salivary alpha-amylase. The direct contagion of emotion has long interested philosophers and psychologists, suggesting perhaps that we are endowed with an evolved, biological pre- paredness to feel, understand, and be inspired by the states of others (Hume, 1739–1740/1990; Lipps, 1903; McDougall, 1908/1923; Nietzsche, 1895/1920; Smith, 1759). In evolutionary biology, this conta- gion or resonance of emotion across individuals is considered particularly adaptive for coordinating the behavior of groups and for fostering the motivated and tailored care of offspring (Bowlby, 1969; de Waal, 2008; Eibl-Eibesfeldt, 1971/1974). In human behav- ior, emotional contagion is described as a simple state in which one simply “catches” the emotions of another, Correspondence should be addressed to: Tony W. Buchanan, Department of Psychology, Saint Louis University, 221 N. Grand Blvd., St. Louis, MO 63103, USA. E-mail: tbuchan7@slu.edu We thank Michelle Hendricks, Dana Hamann, and Chris Schmank for help collecting data, and Clemens Kirschbaum for analyzing saliva samples. We are grateful for feedback on previous versions of this paper from Alicia Hofelich, James Abelson, Ethan Kross, and two anonymous reviewers. This research was funded by a grant to S.D.P. and T.W.B. from the Templeton Foundation. producing a similar internal state in the observer that resulted directly from the observation (Hatfield, Cacioppo, & Rapson, 1993; Hoffman, 2000). Such contagion, also known as the “resonance” of emo- tion among individuals, is widespread, occurs early in development, and exists across species (Preston & de Waal, 2002a). However, it is also often dero- gated as a state that does not require advanced cog- nitive capabilities and can be associated with a self- oriented response to another’s need, motivated more by the desire to reduce one’s own distress than gen- uine concern for the other (reviewed in Eisenberg & Miller, 1987). The perception-action model (PAM) of empathy integrates both views by framing emotional © 2011 Psychology Press, an imprint of the Taylor & Francis Group, an Informa business www.psypress.com/socialneuroscience DOI: 10.1080/17470919.2011.588723