Terrighena Esslin L, Lu Ge, Yuen Wai Ping, Lee Tatia Mc, Keuper Kati
Department of Psychology, Laboratory of Neuropsychology, The University of Hong Kong, Hong Kong.
Laboratory of Social Cognitive Affective Neuroscience, The University of Hong Kong, Hong Kong.
J Pain Res. 2017 Jul 31;10:1821-1830. doi: 10.2147/JPR.S132744. eCollection 2017.
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.
对他人疼痛的观察可能会增强或减轻自身疼痛，然而，决定这种影响方向的边界条件和因素却鲜为人知。当前的研究旨在表明，视觉刺激意识在决定替代性疼痛主要激活增强疼痛敏感性并刺激退缩的行为防御系统，还是激活减弱疼痛敏感性并刺激接近行为的动机系统方面起着关键作用。我们采用了混合因子设计，其中被试间因素为暴露时间（阈下与最佳）和替代性疼痛（疼痛与无疼痛图像），被试内因素为时段（基线与试验），以研究对替代性疼痛图像的视觉意识如何在冷加压试验中影响随后的自身疼痛。在77名健康参与者的样本中评估了自身疼痛耐受性、强度和不愉快程度。结果显示，在所有三项因变量测量中，暴露时间和替代性疼痛之间存在显著的交互作用。在有视觉意识的情况下（最佳条件），与无疼痛相比，替代性疼痛总体上增强了自身疼痛敏感性，表现为疼痛耐受性降低以及疼痛强度和不愉快程度评分升高。相反，在没有视觉意识的情况下（阈下条件），替代性疼痛引发自身疼痛强度和不愉快程度降低，而疼痛耐受性不受影响。这些发现表明，替代性疼痛对防御机制的激活取决于相对复杂的认知过程，而引人注目的是，动机系统是以高度自动的方式被激活，且与刺激意识无关。这样的机制可能已经进化，以促进对受苦个体的共情、保护性接近反应，确保保护性社会群体的生存。
