Doyle Rebecca E, Vidal Stephanie, Hinch Geoff N, Fisher Andrew D, Boissy Alain, Lee Caroline
CSIRO Livestock Industries, New England Highway, Armidale, NSW 2350, Australia.
Behav Processes. 2010 Mar;83(3):349-52. doi: 10.1016/j.beproc.2010.01.019. Epub 2010 Jan 29.
Testing judgement biases of animals may provide insight into their affective states; however important questions about methodologies need to be answered. This experiment investigated the effect of repeated testing using unreinforced, ambiguous cues on the response of sheep to a go/no-go judgement bias test. Fifteen sheep were trained to differentiate between two locations, reinforced respectively with feed (positive) or with the presentation of a dog (negative). The responses to nine ambiguous locations, positioned between the positively and negatively reinforced locations, were tested repeatedly over 3 weeks. Sheep exhibited a symmetrical gradation in response to ambiguous locations between the positive and negative reinforcers. There was a significant decline (P=0.001) in the total number of approaches to the ambiguous positions over time (weeks). This effect of time suggests that sheep learnt that the ambiguous locations were unrewarded. This result supplies evidence of a limitation identified in current judgement bias methodology, due to repeated testing, which has the potential to provide misleading results.
测试动物的判断偏差可能有助于深入了解它们的情感状态；然而，关于方法学的一些重要问题仍有待解答。本实验研究了使用未强化的模糊线索进行重复测试对绵羊在“去/不去”判断偏差测试中的反应的影响。15只绵羊被训练区分两个地点，分别用饲料（正向）或出现狗（负向）进行强化。对位于正向和负向强化地点之间的九个模糊地点的反应在3周内进行了反复测试。绵羊对正向和负向强化物之间的模糊地点表现出对称的渐变反应。随着时间（周数）的推移，对模糊位置的接近总数显著下降（P = 0.001）。时间的这种影响表明绵羊了解到模糊位置没有奖励。这一结果提供了证据，证明由于重复测试，当前判断偏差方法学中存在一个局限性，这有可能产生误导性结果。
