In the eyes of a dog

Posted Jan. 05, 2012, at 7:18 p.m.

Sit a dog in front of a television screen, and it may not always look intently at what it sees. But show a person on that screen who looks directly at the dog and says “hello,” and the canine will pay attention. In fact, a new study shows that a dog will go so far as to follow the gaze of the human on screen when he or she looks to one side or the other — something not even chimps can do.

Researchers already knew that dogs were attuned to human communication signals. In addition to their obvious facility at learning commands, dogs, like young children, can signal where a human puts an object if the human feigns ignorance, even if it’s been moved, and they follow the direction of our finger when we point at things, a task chimps fail at. But are dogs capable of following m ore subtle cues, such as our shifting gaze?

To find out, cognitive scientist Erno Teglas of the Central European University in Budapest adapted a technique that had previously been used only on children. In one example of the test, a child watches a woman on a video screen who has toys on either side of her. The woman then either looks straight toward the camera and says “hello” in a high-pitched voice known to engage children or looks downward and says “hello” in a more dull, low-pitched voice. Then the person looks to the toy on one side or the other for five seconds. Whether a child also looks at the toy on the same side is recorded. To modify this experiment for dogs, Tiglas substituted empty plastic pots for the children’s toys and had a stranger on the screen say “Hi, dog!” in one of the two intonations while looking at the camera or downward. As each dog watches the video, a specially programmed camera below the television screen follows, and records, the dog’s eye movements.

Tiglas and his colleagues used 22 dogs of different breeds for the study. They found that the canines always looked at the person on the video for the same amount of time. But when the person initially directed his or her attention at the dog and spoke in a high-pitched voice, the dog looked at the same pot as the person 69% of the time. When the person avoided eye contact and spoke in a low voice, the dog didn’t look at one pot more often than the other.

The results, published in Current Biology, were almost identical to those seen in 6-month-old human infants. “We were surprised by the high similarity of the performances,” Tiglas says. “Dogs are receptive to these cues in a way that is very similar to infants.”

The precision of the eye-tracking device will allow scientists to develop a new generation of tests on how dogs interact with humans, says Juliane Kaminski, a developmental psychologist at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, who was involved in earlier studies on how dogs interpret finger pointing. “It opens many new opportunities.”

Now that the scientists have shown that the test works on dogs, they plan to separate the two factors — eye contact and tone of voice — to test each one’s effect on the dog’s attention, Tiglas says. They also can compare different dog breeds with each other. This may help answer the question of how dogs’ skills at interpreting human communication have evolved.

“Dog skills with human communication seem to be a special adaptation to live with humans and the result of certain selection pressures during domestication,” Kaminski says. If this is true, researchers would expect dog breeds that have been domesticated the longest to perform best at tests such as gaze following. But don’t plan on being able to compare your dog with all the other neighborhood canines — dogs likely interpret the cues from their owner differently than those from a stranger.

This story is adapted from ScienceNOW, the online daily news service of the journal Science.

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