Call your dog's name, and he may picture your face. That's the conclusion of a new study that suggests a canine has more than treats on his mind when summoned by his master's voice.
In the 10,000 years or more since domestic dogs diverged from their wolf ancestors, man's best friend has developed a variety of social skills to help him get along with people. Compared to wolves and even apes, for example, dogs excel at interpreting human gestures--especially ones that convey the location of hidden food (Science, 22 November 2002). Cognitive scientist Ikuma Adachi and colleagues at Kyoto University in Japan suspected that dogs also might have evolved the ability to form mental images of individual humans.
To investigate, the researchers recruited 28 pooches and their owners. In each experimental session, the dog's owner or another familiar person positioned the dog about a meter away from a computer monitor hidden behind a screen. Then, the researchers played a recording of either the owner or a stranger saying the dog's name five times through speakers in the monitor. Finally, the researchers removed the screen to reveal a still image of either the owner's face or the face of a stranger. Video cameras recorded the dogs' reactions.
When the owner's voice preceded the owner's face, dogs looked at the screen for about 6 seconds on average. The same was true when the researchers paired a strange voice with a strange face. But when a stranger's face followed the owner's voice (or vice versa), the dogs spent an extra second or two staring at the monitor, suggesting that they realized something was amiss, Adachi says. (Similar methods have been used to test face recognition in human infants (ScienceNOW, 17 May 2002). Adachi suspects that the sound of an owner's voice conjures up a mental image of the owner's face--and leads to confusion when another face appears instead. He and his colleagues report their findings in the January issue of Animal Cognition.
"This was a very well-designed experiment with a very exciting finding," says Brian Hare, a biological anthropologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. The findings suggest that dogs form surprisingly sophisticated mental representations of people, Hare says. "They have a picture in their mind of their owner, and they can think about it and make predictions based on that picture."