Neave Heather W, Daros Rolnei R, Costa João H C, von Keyserlingk Marina A G, Weary Daniel M
Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia, Canada.
PLoS One. 2013 Dec 4;8(12):e80556. doi: 10.1371/journal.pone.0080556. eCollection 2013.
Pain is defined as an unpleasant sensory and emotional experience associated with actual or potential tissue damage, but emotional states are difficult to directly assess in animals. Researchers have assessed pain using behavioural and physiological measures, but these approaches are limited to understanding the arousal rather than valence of the emotional experience. Cognitive bias tasks show that depressed humans judge ambiguous events negatively and this technique has been applied to assess emotional states in animals. However, limited research has examined how pain states affect cognitive processes in animals. Here we present the first evidence of cognitive bias in response to pain in any non-human species. In two experiments, dairy calves (n = 17) were trained to respond differentially to red and white video screens and then tested with unreinforced ambiguous colours in two or three test sessions before and two sessions after the routine practice of hot-iron disbudding. After disbudding calves were more likely to judge ambiguous colours as negative. This 'pessimistic' bias indicates that post-operative pain following hot-iron disbudding results in a negative change in emotional state.
疼痛被定义为一种与实际的或潜在的组织损伤相关的不愉快的感觉和情感体验，但情感状态在动物中难以直接评估。研究人员已使用行为和生理测量方法来评估疼痛，但这些方法仅限于理解情感体验的唤醒而非效价。认知偏差任务表明，抑郁的人类会对模糊事件做出负面判断，并且这种技术已被应用于评估动物的情感状态。然而，仅有有限的研究考察了疼痛状态如何影响动物的认知过程。在此，我们首次呈现了任何非人类物种对疼痛产生认知偏差的证据。在两项实验中，对17头奶牛犊进行训练，使其对红色和白色视频屏幕做出不同反应，然后在热烙铁去角常规操作之前的两到三个测试环节以及之后的两个环节中，用无强化的模糊颜色对其进行测试。去角后，犊牛更有可能将模糊颜色判断为负面。这种“悲观”偏差表明，热烙铁去角后的术后疼痛会导致情感状态发生负面变化。
