Messerli Research Institute, University of Veterinary Medicine Vienna, Medical University of Vienna, University of Vienna Vienna, Austria ; Department of Cognitive Biology, University of Vienna Vienna, Austria ; Clever Dog Lab Society Vienna, Austria.
Front Psychol. 2012 Dec 26;3:558. doi: 10.3389/fpsyg.2012.00558. eCollection 2012.
Dogs are exceptionally successful at interpreting human pointing gestures to locate food hidden in one of two containers. However, it has repeatedly been questioned whether dogs rely on the pointing gesture or their success is increased by subtle cues from their human handler. In two experiments we used a standard two-way object-choice task to focus on this potential Clever Hans effect. We investigated if and how owners' knowledge and beliefs influenced their dogs' performance. In two experiments, as is typical in such pointing tasks, the owners sat behind their dogs, in close auditory and tactile contact with them. In Experiment 1, we systematically manipulated the owners' knowledge of whether or not their dog should follow the pointing gesture, but at the same time instructed the owners to refrain from influencing the choice of their dog. We found no influence of subtle cues from the owners, if indeed they existed: dogs in the different groups followed the pointing uniformly. Furthermore, in the absence of pointing dogs chose randomly, even though the owners had been informed about the location of the reward. In Experiment 2, owners were instructed to actively influence the choice of their dogs, and they, indeed, succeeded in sending their dogs to the container they believed to be baited. However, their influence was significantly weaker if the experimenter had previously pointed to the other location. Overall the pointing gesture seems to have a strong effect on the choice of dogs in an object-choice task. Pointing can lead the dogs to success without help from their owners as well as it can counteract clear directional instructions provided by the owners.
狗在解释人类的指示手势以找到藏在两个容器之一中的食物方面非常成功。然而，人们反复质疑狗是否依赖指示手势，或者它们的成功是否因人类饲养员的微妙暗示而增加。在两项实验中，我们使用标准的双向物体选择任务来关注这种潜在的聪明汉斯效应。我们调查了主人的知识和信念是否以及如何影响他们的狗的表现。在两项实验中，与典型的指示任务一样，主人坐在狗的后面，与狗保持密切的听觉和触觉接触。在实验 1 中，我们系统地操纵了主人是否知道他们的狗应该遵循指示手势，但同时指示主人不要影响狗的选择。如果确实存在来自主人的微妙暗示，我们没有发现它们的影响：狗在不同的组中一致地遵循指示。此外，即使主人被告知奖励的位置，狗在没有指示的情况下也会随机选择。在实验 2 中，主人被指示积极影响他们的狗的选择，他们确实成功地将他们的狗送到他们认为有诱饵的容器。然而，如果实验者之前指向另一个位置，他们的影响明显减弱。总的来说，在物体选择任务中，指示手势似乎对狗的选择有很大的影响。即使没有主人的帮助，指示也可以引导狗取得成功，也可以抵消主人提供的明确的方向指示。
