Science Watch

When Alexandra Horowitz, PhD, comes home from work, her new puppy, Finnegan, rushes to the door to greet her. The lab/pointer mix capers around Horowitz's feet, slobbers on her pants and seems overjoyed to see her.

"He's awfully cute, there's no denying that," says Horowitz, a psychology professor at Barnard College.

That cuteness is no accident. New research by Horowitz and others suggests that Finnegan--and the roughly 52 million pet dogs in the United States--are tailor-made to exploit our tendency to attribute human qualities to everything that moves. And they are good at it: While we poison rats and stomp on bugs, Americans spend nearly $10 billion a year on vet services and $15 billion on pet food--more than we spend on baby food.

"People really do treat them like part of the family," Horowitz notes.

However, dogs' membership in our society, and their understanding of the human world, may be more illusion than reality. Specifically, their tendency to pay attention and interact with humans may mask an inner life that's not much like our own.

Sit, stay, smile

Over the 15,000 years that humans and dogs have lived together, dogs have evolved to behave like happy toddlers, acting in ways that sharply distinguish them from other animals.

Wolves, for example, don't make eye contact with other wolves. But dogs look us right in the eyes, a behavior that we read as engaging and friendly, says Horowitz. They inspire us to nurture and care for them with their large foreheads and big, round eyes--infant-like features that evolved through human-directed breeding, she notes. Even the triangular shape of dogs' heads--resulting in a "smile" whenever they open their mouth to pant--may play a role in dogs' success at getting favors from humans.

"They are not smiling; that is just a physiological feature," Horowitz says. "But it helps in our impression that they are agreeable creatures."

The key to dogs' charm, though, may lay in the close attention they pay to humans, says Monique Udell, a psychology graduate student at the University of Florida.

In a study published this year in the Journal of Comparative Psychology (Vol. 122, No. 1), Udell found that when people point or bow toward a cup containing hidden food, dogs easily interpret the signal and find the food. This may seem obvious, but chimpanzees and other primates don't understand pointing, past research has shown.

Similarly, dogs pay close attention to where we are looking, found Christine Schwab, a psychology graduate student at the University of Vienna in Austria. In a study in 2006, in the Journal of Comparative Psychology, (Vol. 120, No. 3) she found that after being told to "sit," dogs tended to stay put as long as their owners were looking toward them. Dogs disobeyed the command when their owners were distracted by TV or if they turned their backs.

All this adds up to an animal that makes for a fun study participant and good company, says Udell.

"They want to interact; they want to play games," says Udell. "You just don't get that with a lot of other species. Sea lions will get bored and wander off."

Jealous hamsters?

In addition to inspiring us to spend billions on dog food, dogs' responsiveness to human cues gives us the sense that they have emotions and thoughts similar to ours--an assumption that can lead to problems for both dogs and humans.

For instance, if you have someone else watch your dog for the weekend, you may return to find your apartment strewn with mattress stuffing. It's natural, in such circumstances, for dog owners to assume that Fido's "mad" at them for leaving. However, it's equally likely that the animal was just bored, says Udell.

"Many times, the behavior is not addressed because people miss the point," she notes. For instance, an owner may try to mend her relationship with the "miffed" dog by giving it extra attention, which would reinforce its destructive habits.

Despite such pitfalls, people commonly assume that dogs have inner lives similar to humans'. A 2007 study in Cognition and Emotion (Vol. 22, No. 1) found that 81 percent of dog owners had seen their animals act "jealous" and 74 percent had seen them act "guilty." (Incidentally, 15 percent of the hamsters in the study had expressed guilt, and 17 percent had acted jealous, according to their owners.)

Study author Paul Morris, PhD, believes that the consistency among dog behaviors reported by owners suggests that dogs do, in fact, experience jealousy. For example, the dogs in the study tended to act "jealous" when their owners paid attention to another dog or person. The jealous dogs would then bark or nuzzle their owners.

"People's claims of jealousy in dogs are grounded in a very coherent set and a very limited set of behaviors and contexts," says Morris, a psychology professor at the University of Portsmouth in England. "They are not arbitrary anthropomorphic projections."

But human jealousy is underpinned by a slew of complex cognitions, including a sense of injustice, says Horowitz. A dog seeking attention may simply be responding to its owner in an adaptive, potentially hardwired way.

"It would probably pay to be sensitive to who is getting the attention in the household, to who in the family is getting all the food," says Horowitz. A dog may act jealous, but there's no reason to believe it feels human-like jealousy, she adds.

In fact, research suggests that dogs may lack the cognitive machinery to have the inner lives we often attribute to them, says William A. Roberts, PhD, a psychology professor at the University of Western Ontario. For instance, in an as-yet-unpublished study, Roberts found that dogs lack metamemory--knowing what you know and what you don't--an ability that rats and chimps have demonstrated.

"When you get away from the social area, dogs don't seem to be as cognitively competent as a lot of other animals," he says.

Yet dogs have, after all, evolved the ability to evoke some of our best qualities, says Paul Marcus, PhD, a New York-based psychoanalyst who studies human-dog relationships.

"They generate in us a sort of affection that doesn't have any ambivalence," says Marcus. "There is a kind of simplicity or gentle elegance, really, to the way they live."