title: You turn me cold: evidence for temperature contagion.
abstract: BACKGROUND
  During social interactions, our own physiological responses influence those of others. Synchronization of physiological (and behavioural) responses can facilitate emotional understanding and group coherence through inter-subjectivity. Here we investigate if observing cues indicating a change in another's body temperature results in a corresponding temperature change in the observer.
  
  
  METHODS
  Thirty-six healthy participants (age; 22.9±3.1 yrs) each observed, then rated, eight purpose-made videos (3 min duration) that depicted actors with either their right or left hand in visibly warm (warm videos) or cold water (cold videos). Four control videos with the actors' hand in front of the water were also shown. Temperature of participant observers' right and left hands was concurrently measured using a thermistor within a Wheatstone bridge with a theoretical temperature sensitivity of <0.0001°C. Temperature data were analysed in a repeated measures ANOVA (temperature × actor's hand × observer's hand).
  
  
  RESULTS
  Participants rated the videos showing hands immersed in cold water as being significantly cooler than hands immersed in warm water, F(1,34) = 256.67, p<0.001. Participants' own hands also showed a significant temperature-dependent effect: hands were significantly colder when observing cold vs. warm videos F(1,34) = 13.83, p = 0.001 with post-hoc t-test demonstrating a significant reduction in participants' own left (t(35) = -3.54, p = 0.001) and right (t(35) = -2.33, p = 0.026) hand temperature during observation of cold videos but no change to warm videos (p>0.1). There was however no evidence of left-right mirroring of these temperature effects p>0.1). Sensitivity to temperature contagion was also predicted by inter-individual differences in self-report empathy.
  
  
  CONCLUSIONS
  We illustrate physiological contagion of temperature in healthy individuals, suggesting that empathetic understanding for primary low-level physiological challenges (as well as more complex emotions) are grounded in somatic simulation.
authors.affiliation: Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom.
authors.forename: Ella A
authors.initials: EA
authors.lastname: Cooper
authors.affiliation: Institute of Cognitive Neuroscience, UCL, London, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Garlick
authors.affiliation: Wellcome Trust Centre for Neuroimaging, UCL, London, United Kingdom.
authors.forename: Eric
authors.initials: E
authors.lastname: Featherstone
authors.affiliation: Behavioural and Clinical Neurosciences Institute, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Valerie
authors.initials: V
authors.lastname: Voon
authors.affiliation: Institute of Cognitive Neuroscience, UCL, London, United Kingdom; Department of Social Neuroscience, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany.
authors.forename: Tania
authors.initials: T
authors.lastname: Singer
authors.affiliation: Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom; Institute of Cognitive Neuroscience, UCL, London, United Kingdom; Sackler Centre for Consciousness Science, University of Sussex, Brighton, United Kingdom; Sussex Partnership NHS Trust, Brighton, United Kingdom.
authors.forename: Hugo D
authors.initials: HD
authors.lastname: Critchley
authors.affiliation: Brighton and Sussex Medical School, University of Sussex, Brighton, United Kingdom; Institute of Cognitive Neuroscience, UCL, London, United Kingdom; Sackler Centre for Consciousness Science, University of Sussex, Brighton, United Kingdom; Sussex Partnership NHS Trust, Brighton, United Kingdom.
authors.forename: Neil A
authors.initials: NA
authors.lastname: Harrison
mesh_terms: D000328:Adult; D001831:Body Temperature / Q000502:physiology*; D001833:Body Temperature Regulation; D004644:Emotions; D004645:Empathy; D005260:Female; D006225:Hand / Q000502:physiology; D006339:Heart Rate; D006801:Humans; D008297:Male; D033281:Nontherapeutic Human Experimentation; D011795:Surveys and Questionnaires