Adachi Ikuma, Kuwahata Hiroko, Fujita Kazuo
Department of Psychology, Graduate School of Letters, Kyoto University, Yoshida-honmachi, Sakyo, Kyoto, 606-8501, Japan.
Anim Cogn. 2007 Jan;10(1):17-21. doi: 10.1007/s10071-006-0025-8. Epub 2006 Jun 21.
We tested whether dogs have a cross-modal representation of human individuals. We presented domestic dogs with a photo of either the owner's or a stranger's face on the LCD monitor after playing back a voice of one of those persons. A voice and a face matched in half of the trials (Congruent condition) and mismatched in the other half (Incongruent condition). If our subjects activate visual images of the voice, their expectation would be contradicted in Incongruent condition. It would result in the subjects' longer looking times in Incongruent condition than in Congruent condition. Our subject dogs looked longer at the visual stimulus in Incongruent condition than in Congruent condition. This suggests that dogs actively generate their internal representation of the owner's face when they hear the owner calling them. This is the first demonstration that nonhuman animals do not merely associate auditory and visual stimuli but also actively generate a visual image from auditory information. Furthermore, our subject also looked at the visual stimulus longer in Incongruent condition in which the owner's face followed an unfamiliar person's voice than in Congruent condition in which the owner's face followed the owner's voice. Generating a particular visual image in response to an unfamiliar voice should be difficult, and any expected images from the voice ought to be more obscure or less well defined than that of the owners. However, our subjects looked longer at the owner's face in Incongruent condition than in Congruent condition. This may indicate that dogs may have predicted that it should not be the owner when they heard the unfamiliar person's voice.
我们测试了狗是否具有对人类个体的跨模态表征。在播放其中一人的声音后，我们在液晶显示器上向家犬展示主人或陌生人的面部照片。在一半的试验中，声音和面孔相匹配（一致条件），在另一半试验中不匹配（不一致条件）。如果我们的实验对象激活了声音的视觉图像，那么在不一致条件下，它们的预期就会产生矛盾。这将导致实验对象在不一致条件下的注视时间比在一致条件下更长。我们的实验对象狗在不一致条件下对视觉刺激的注视时间比在一致条件下更长。这表明，当狗听到主人呼唤它们时，它们会主动构建主人面孔的内部表征。这是首次证明非人类动物不仅能将听觉和视觉刺激联系起来，还能从听觉信息中主动生成视觉图像。此外，与主人的声音之后出现主人的面孔的一致条件相比，在陌生人的声音之后出现主人的面孔的不一致条件下，我们的实验对象对视觉刺激的注视时间也更长。对陌生声音做出特定的视觉图像反应应该是困难的，并且来自该声音的任何预期图像都应该比主人的图像更模糊或更不清晰。然而，我们的实验对象在不一致条件下对主人面孔的注视时间比在一致条件下更长。这可能表明，当狗听到陌生人的声音时，它们可能已经预测到那不是主人。
