Animal Welfare Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, BC, Canada.
PLoS One. 2021 Mar 1;16(3):e0247808. doi: 10.1371/journal.pone.0247808. eCollection 2021.
People often express concern for the welfare of farm animals, but research on this topic has relied upon self-report. Facial expressions provide a quantifiable measure of emotional response that may be less susceptible to social desirability bias and other issues associated with self-report. Viewing other humans in pain elicits facial expressions indicative of empathy. Here we provide the first evidence that this measure can also be used to assess human empathetic responses towards farm animals, showing that facial expressions respond reliably when participants view videos of farm animals undergoing painful procedures. Participants (n = 30) were asked to watch publicly sourced video clips of cows and pigs undergoing common management procedures (e.g. disbudding, castration, tail docking) and control videos (e.g. being lightly restrained, standing). Participants provided their subjective rating of the intensity of 5 negative emotions (pain, sadness, anger, fear, disgust) on an 11-point Likert scale. Videos of the participants (watching the animals) were scored for intensity of unpleasantness of the participants' facial expression (also on an 11-point Likert scale) by a trained observer who was blind to treatment. Participants showed more intense facial expressions while viewing painful procedures versus control procedures (mean ± SE Likert; 2.4 ± 0.08 versus 0.6 ± 0.17). Participants who reported more intense negative responses also showed stronger facial expressions (slope ± SE = 0.4 ± 0.04). Both the self-reported and facial measures varied with species and procedure witnessed. These results indicate that facial expressions can be used to assess human-animal empathy.
人们常常关心农场动物的福利，但这方面的研究依赖于自我报告。面部表情提供了一种可量化的情绪反应衡量方式，可能较少受到社会期望偏差和其他与自我报告相关的问题的影响。看到他人感到痛苦会引起同理心的面部表情。在这里，我们首次提供了证据表明，这种衡量方法也可以用于评估人类对农场动物的同理心反应，表明当参与者观看农场动物接受痛苦程序的视频时，面部表情会可靠地做出反应。参与者（n=30）被要求观看公开来源的奶牛和猪接受常见管理程序（例如去角、去势、断尾）和对照视频（例如轻度约束、站立）的视频剪辑。参与者在 11 点李克特量表上对 5 种负面情绪（疼痛、悲伤、愤怒、恐惧、厌恶）的强度进行主观评分。通过一名受过训练的观察者对参与者观看动物时的面部表情的不愉快强度（也在 11 点李克特量表上）进行评分，观察者对治疗情况一无所知。与对照程序（平均±SE 李克特；2.4±0.08 对 0.6±0.17）相比，参与者在观看痛苦程序时表现出更强烈的面部表情。报告更强烈负面反应的参与者也表现出更强的面部表情（斜率±SE=0.4±0.04）。自我报告和面部测量都随所见物种和程序而变化。这些结果表明，面部表情可用于评估人类与动物的同理心。
