Journal of Pain Research (Jul 2017)
Effects of vicarious pain on self-pain perception: investigating the role of awareness
Abstract
Esslin L Terrighena,1,2 Ge Lu,1 Wai Ping Yuen,1 Tatia M C Lee,1–4 Kati Keuper1,2,5 1Department of Psychology, Laboratory of Neuropsychology, The University of Hong Kong, Hong Kong; 2Laboratory of Social Cognitive Affective Neuroscience, The University of Hong Kong, Hong Kong; 3The State Key Laboratory of Brain and Cognitive Sciences, Hong Kong; 4Institute of Clinical Neuropsychology, The University of Hong Kong, Hong Kong; 5Institute for Biomagnetism and Biosignalanalysis, University of Münster, Münster, Germany Abstract: The observation of pain in others may enhance or reduce self-pain, yet the boundary conditions and factors that determine the direction of such effects are poorly understood. The current study set out to show that visual stimulus awareness plays a crucial role in determining whether vicarious pain primarily activates behavioral defense systems that enhance pain sensitivity and stimulate withdrawal or appetitive systems that attenuate pain sensitivity and stimulate approach. We employed a mixed factorial design with the between-subject factors exposure time (subliminal vs optimal) and vicarious pain (pain vs no pain images), and the within-subject factor session (baseline vs trial) to investigate how visual awareness of vicarious pain images affects subsequent self-pain in the cold-pressor test. Self-pain tolerance, intensity and unpleasantness were evaluated in a sample of 77 healthy participants. Results revealed significant interactions of exposure time and vicarious pain in all three dependent measures. In the presence of visual awareness (optimal condition), vicarious pain compared to no-pain elicited overall enhanced self-pain sensitivity, indexed by reduced pain tolerance and enhanced ratings of pain intensity and unpleasantness. Conversely, in the absence of visual awareness (subliminal condition), vicarious pain evoked decreased self-pain intensity and unpleasantness while pain tolerance remained unaffected. These findings suggest that the activation of defense mechanisms by vicarious pain depends on relatively elaborate cognitive processes, while – strikingly – the appetitive system is activated in highly automatic manner independent from stimulus awareness. Such mechanisms may have evolved to facilitate empathic, protective approach responses toward suffering individuals, ensuring survival of the protective social group. Keywords: observation of pain, approach, defense, pain tolerance
