The Effects of Measuring Emotion: Physiological Reactions to Emotional Situations Depend on whether Someone Is Asking Karim S. Kassam 1 *, Wendy Berry Mendes 2 * 1 Department of Social and Decision Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, United States of America, 2 Department of Psychiatry, University of California San Francisco, San Francisco, California, United States of America Abstract Measurement effects exist throughout the sciences–the act of measuring often changes the properties of the observed. We suggest emotion research is no exception. The awareness and conscious assessment required by self-report of emotion may significantly alter emotional processes. In this study, participants engaged in a difficult math task designed to induce anger or shame while their cardiovascular responses were measured. Half of the participants were asked to report on their emotional states and appraise their feelings throughout the experiment, whereas the other half completed a control questionnaire. Among those in the anger condition, participants assigned to report on their emotions exhibited qualitatively different physiological responses from those who did not report. For participants in the shame condition, there were no significant differences in physiology based on the self-report manipulation. The study demonstrates that the simple act of reporting on an emotional state may have a substantial impact on the body’s reaction to an emotional situation. Citation: Kassam KS, Mendes WB (2013) The Effects of Measuring Emotion: Physiological Reactions to Emotional Situations Depend on whether Someone Is Asking. PLoS ONE 8(6): e64959. doi:10.1371/journal.pone.0064959 Editor: Tom Denson, The University of South Wales, Australia Received December 4, 2012; Accepted April 22, 2013; Published June 5, 2013 Copyright: ß 2013 Kassam, Mendes. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This research was supported by funding from National Heart, Lung and Blood Institute (NHLBI) grant (HL079383) to WBM. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. * E-mail: kskassam@cmu.edu (KSK); wendy.mendes@ucsf.edu (WBM) Introduction Throughout the sciences, observation is known to alter the observed. In physics, observing a particle requires another particle to interact with it, changing the properties of the particle to be observed [1]. In computer science, adding a debugger changes memory allocation, which can alter the behavior of target code. In electrical engineering, measurement of current in a circuit entails adding a voltmeter, which necessarily changes current flow. Measurement effects may also be important in emotion research– how people feel could depend on whether someone is asking. Reporting how we are feeling requires awareness and conscious assessment of our emotional states, and these processes may alter emotional experiences. Emotions are complex processes involving multiple response channels, including physiological systems, facial and vocal expressive tendencies, and cognition [2][3][4]. These channels influence each other in a process that extends over time [5]: emotional events trigger sequences of neural activity [6][7][8], which result in changes in autonomic and neuroendocrine systems [9][10]. Reporting how we are feeling may interrupt these processes, replacing the characteristic thoughts and appraisals of the emotion with awareness of the emotion itself. This shift of attention and change in cognition may alter other aspects of emotional response. As a result, the emotional process on which we have been asked to report could be fundamentally altered. An assumption that emotional processes will return to normal operation following self-report is tenuous. Subjective feelings, the conscious component of emotional response, don’t arise from simple, passive perception. Awareness of our emotional states requires focal attention [11], as well as an interpretive process that tends to recruit a wide range of information [12]. Though we may have the impression that feelings simply appear in consciousness, their generation entails an active process that consumes cognitive resources [13]. Such complex cognitions are likely to interact with emotional response, which involves its own set of characteristic thoughts [14]. That conscious processing is capable of impacting emotion is well documented. Detailed, causal analyses of past emotional experiences can have a significant impact on current emotional states. Writing about negative emotional experiences for a few minutes every day can lead to significant physical and mental health improvements [15][16]. Talking about past emotional experiences can also affect present physiology, with emotional disclosure being associated with changes in skin conductance levels and cardiovascular physiology [17][18]. Attempting to understand the causes of negative emotion thus serves to ameliorate their negative effects. Reflective reasoning can also mitigate the negative effects of ongoing emotional experiences. Reappraising an emotional situation to be less impactful (e.g. consciously adopting the mindset of a medical student when watching a disgusting video) decreases self-reported emotional intensity, reduces emo- tion-related expressive behavior, and moderates a number of physiological variables [19][20]. Though diary writing and reappraisal require substantial cognitive processing, more subtle manipulations of awareness PLOS ONE | www.plosone.org 1 June 2013 | Volume 8 | Issue 6 | e64959