Soto Fabian A, Wasserman Edward A
Department of Psychology, University of Iowa, Iowa City, IA 52242, USA.
J Vis. 2011 Mar 31;11(3):24. doi: 10.1167/11.3.24.
The human visual system appears to process the identity of faces separately from their emotional expression, whereas the human visual system does not appear to process emotional expression separately from identity. All current explanations of this visual processing asymmetry implicitly assume that it arises because of the organization of a specialized human face perception system. A second possibility is that this finding reflects general principles of perceptual processing. Studying animals that are unlikely to have evolved a specialized face perception system may shed fresh light on this issue. We report two experiments that investigated the interaction of identity and emotional expression in pigeons' perception of human faces. Experiment 1 found that pigeons perceive the similarity among faces sharing identity and emotion, and that these two dimensions are integral according to a spatial model of generalization. Experiment 2 found that pigeons' discrimination of emotion was reliably affected by irrelevant variations in identity, whereas pigeons' discrimination of identity was not reliably affected by irrelevant variations in emotion. Thus, the asymmetry previously reported in human studies was reproduced in our pigeon study. These results challenge the view that a specialized human face perception system must underlie this effect.
人类视觉系统似乎会将面部的身份与情感表达分开处理，而人类视觉系统似乎不会将情感表达与身份分开处理。目前对这种视觉处理不对称现象的所有解释都隐含地假定，它的出现是由于专门的人类面部感知系统的组织方式。另一种可能性是，这一发现反映了感知处理的一般原则。研究不太可能进化出专门面部感知系统的动物，可能会为这个问题带来新的启示。我们报告了两项实验，研究了鸽子对面部的感知中身份与情感表达的相互作用。实验1发现，鸽子能够感知具有相同身份和情感的面部之间的相似性，并且根据泛化的空间模型，这两个维度是不可分割的。实验2发现，身份的无关变化会可靠地影响鸽子对情感的辨别，而情感的无关变化不会可靠地影响鸽子对身份的辨别。因此，我们在鸽子研究中重现了先前在人类研究中报告的不对称现象。这些结果挑战了这样一种观点，即这种效应必须基于专门的人类面部感知系统。
