Dog owners often compare their pets to toddlers; many even treat their pooches like kids. It's easy to label such comparisons sentimental. But a new study suggests that the owners are right. A team of scientists has discovered that dogs behave surprisingly like 10-month-old infants on a classic psychological test--though there is one important difference.
Curious about how dogs' minds may have changed through domestication, József Topál, a cognitive ethologist at the Hungarian Academy of Sciences in Budapest, and colleagues gave 36 dogs a test called the object permanence task. As developed for infants, the test works like this: An experimenter hides a toy in location "A" a few times while looking at a baby and talking to him ("Look, I have this nice ball!"). When asked to find the toy, the baby always goes to location "A." The experimenter then hides the toy at location "B," again while interacting with the baby. But this time, when asked to find the toy, the baby continues to search for it at location "A." The findings hold, even when a team changes experimenters midtest. Researchers believe that infants make this error because they believe the adults have taught them something fundamental about the world (i.e., "Your toy will always be at location 'A'").
Dogs, it turns out, also make the same mistake--up to a point. In the canine tests, an experimenter first used social cues--"Spot! Watch!" and eye gaze--and hid the toy several times at location "A." When the person then spoke these same words but hid the ball at location "B," the dogs persisted in searching for the toy at "A"--even though "they had clearly watched" the person hide it at B, says Topál. Wolves that were hand-reared and strongly socialized did not make this mistake. All of this suggests, says Topál, that dogs and young humans respond to similar social cues, probably because dogs have lived alongside us for so long and consequently have evolved a more sophisticated understanding of human communication.
But dogs don't learn about the world from us the way babies do. When the team switched experimenters midstream--i.e., when one person hid the toy at location "A," and a second person hid the toy at location "B"--dogs stopped making the mistake. They began searching for the toy at location "B." This indicates, says Topál, that dogs aren't learning a rule from humans. Instead, they're just following orders: When a different person hides the toy at "B," they no longer pay attention to the previous experimenter’s instructions to search for the toy at A. The team reports its findings tomorrow in Science.
"It's a brilliant study," says Brian Hare, a cognitive ethologist at Duke University in Durham, North Carolina. Hare says it "cements the differences" between the ability of wolves and dogs to use social cues, such as words and eye contact. And the striking degree of those differences, adds Marc Bekoff, a cognitive ethologist at the University of Colorado, Boulder, shows how "great an effect domestication had on the behavior of dogs." Also, because dogs are so much more like humans in understanding the importance of our social cues, they offer the best animal model yet for investigating the evolution of our own social skills, the team reports.