Pitteri Elisa, Mongillo Paolo, Carnier Paolo, Marinelli Lieta, Huber Ludwig
Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro, PD, Italy.
Messerli Research Institute, University of Veterinary Medicine Vienna, Medical University of Vienna, and University of Vienna, Vienna, Austria.
PLoS One. 2014 Sep 24;9(9):e108176. doi: 10.1371/journal.pone.0108176. eCollection 2014.
Dogs exhibit characteristic looking patterns when looking at human faces but little is known about what the underlying cognitive mechanisms are and how much these are influenced by individual experience. In Experiment 1, seven dogs were trained in a simultaneous discrimination procedure to assess whether they could discriminate a) the owner's face parts (eyes, nose or mouth) presented in isolation and b) whole faces where the same parts were covered. Dogs discriminated all the three parts of the owner's face presented in isolation, but needed fewer sessions to reach the learning criterion for the eyes than for both nose and mouth. Moreover, covering the eyes region significantly disrupted face discriminability compared to the whole face condition while such difference was not found when the nose or mouth was hidden. In Experiment 2, dogs were presented with manipulated images of the owner's face (inverted, blurred, scrambled, grey-scale) to test the relative contribution of part-based and configural processing in the discrimination of human faces. Furthermore, by comparing the dogs enrolled in the previous experiment and seven 'naïve' dogs we examined if the relative contribution of part-based and configural processing was affected by dogs' experience with the face stimuli. Naïve dogs discriminated the owner only when configural information was provided, whereas expert dogs could discriminate the owner also when part-based processing was necessary. The present study provides the first evidence that dogs can discriminate isolated internal features of a human face and corroborate previous reports of salience of the eyes region for human face processing. Although the reliance on part-perception may be increased by specific experience, our findings suggest that human face discrimination by dogs relies mainly on configural rather than on part-based elaboration.
狗在看人类面孔时会表现出特定的注视模式，但对于其潜在的认知机制以及这些机制受个体经验影响的程度，我们知之甚少。在实验1中，七只狗接受了同时辨别程序训练，以评估它们是否能够辨别：a）单独呈现的主人面部部分（眼睛、鼻子或嘴巴），以及b）相同部分被遮盖的整幅面孔。狗能够辨别单独呈现的主人面部的所有三个部分，但与辨别鼻子和嘴巴相比，达到眼睛辨别学习标准所需的训练次数更少。此外，与整幅面孔条件相比，遮盖眼睛区域显著干扰了面孔的可辨别性，而遮盖鼻子或嘴巴时则未发现这种差异。在实验2中，向狗展示了主人面部的处理图像（倒置、模糊、打乱、灰度），以测试基于部分的处理和整体结构处理在人类面孔辨别中的相对作用。此外，通过比较参与前一个实验的狗和七只“未接触过的”狗，我们研究了基于部分的处理和整体结构处理的相对作用是否受狗对面部刺激的经验影响。未接触过的狗只有在提供整体结构信息时才能辨别主人，而有经验的狗在需要基于部分的处理时也能辨别主人。本研究提供了首个证据，表明狗能够辨别人类面孔的孤立内部特征，并证实了先前关于眼睛区域在人类面孔处理中显著突出的报道。虽然特定经验可能会增加对部分感知的依赖，但我们的研究结果表明，狗对人类面孔的辨别主要依赖于整体结构而非基于部分的精细加工。
