Public Relations Office March 21, 2013
Sadahiko Nakajima, Ph.D., Professor of Kwansei Gakuin University in the Department of Integrated Psychological Sciences in the School of Humanities
Following his graduation from Sophia University’s Psychology Department in the Faculty of Literature, Dr. Nakajima undertook graduate research in animal behavioral intelligence at Keio University. As an overseas special researcher for the Japan Society for the Promotion of Science, he studied at the University of Pennsylvania. He then served as an assistant professor at Kwansei Gakuin University in the School of Humanities, after which he became a full professor in 2009. He specializes in animal psychology and the psychology of learning. He was formerly the editor-in-chief of the Journal of Society for the Study of Human Animal Relations. He also serves as a permanent member of the editorial board of “Research on Animal Psychology” for the Japanese Society for Animal Psychology. He is the author of “Animal Learning” and co-author of “Psychology of Learning.”
Among the various works of photographer Fumiaki Fukuda is a photo collection titled, “If You Love Her, She Looks Like You.” The collection, which comprises two-shot pictures of 64 famous and ordinary people with their pet dogs, offers an amusing look at the degree of physical resemblance between dogs and their owners.
As in the examples shown above, dogs often resemble their owners, and the topic is one of frequent discussion. However, there are also cases that indicate very little resemblance, if any. Judgment on whether or not there is a resemblance may be in the eye of the beholder. For this reason it is necessary to sufficiently collect objective, unbiased data and analyze it as a means to respond the question of whether dogs resemble their owners in general terms.
A few research studies on similarities between the faces of dogs and their owners have been reported overseas, and consequently we investigated whether the statement holds true for Japan.
First, we took headshots of 40 dog owners, and then we took headshots of their 40 dogs (all dogs are purebred but of various breeds). Subsequently, we performed various experiments using the headshots.
In one experiment, when 70 judging examinees who had not met the dogs and owners thus depicted were shown photos of dogs and their owners and matched them at will, a percentage of correct answers was significantly higher than the expected coincidental level was obtained. It has also become clear that the judging examinees had combined the pictures based on the degree of similarity between dogs’ and owners’ faces.
In all the other experiments, we obtained the results affirming the resemblance between dogs and their owners. Thus we were able to verify that dogs' faces resemble their owners'. However, if this is true, why are they similar? Further research is needed in order to answer that question, but thus far two assumptions have been proposed. The first assumption is that “people have dogs whose faces originally are similar to their own.” Since we see our faces in the mirror every day, we are familiar with and sense attachment to our own faces. Consequently, people may choose dogs whose faces resemble them.
The second assumption is that “dogs gradually become similar to their owners while being kept as pets.” For comparison, one study report asserts that human couples develop facial similarities through living together, and the following possibilities are introduced as the reason: (a) They eat the same food (trend toward obesity due to a high-fat diet); (b) they live in the same climate (the influence of sunburn or temperature); and (c) they go through the same experiences (happy or sad emotions are etched on their faces). Apparently, it is necessary to study such possibilities between dogs and their owners as well.
Incidentally, not only is the existence or degree of facial similarity an interesting research theme but the similarity of characteristics is as well. For the preparation of such research, in our research room we have begun to develop character tests for dogs and their owners.