Psychologists have a clever way to test self-awareness in people. A researcher might place a mark on a sleeping child’s forehead — and unaware. When the child wakes up, the researcher then asks the child to look into a mirror. If the child touches the mark on his/her own face after seeing the mark in the mirror, then he/she has passed the test. Touching the mark shows that the child understands “the child in the mirror is me”. Most children over the age of three pass the test. One Asian elephant has too, so do some dolphins and chimpanzees. 

Dogs, however, fail. They sniff the mirror or urinate on it. But they ignore the mark. This doesn’t mean, however, that they aren’t self-aware, argues Roberto Cazzolla Gatti, who studies animal behavior at Tomsk State University in Russia.The scent(嗅觉) tells a dog what happened in the environment, explains Gatti. A dog’s own scent, however, usually doesn’t provide new information. So if a dog recognizes its own smell, it shouldn’t need to sniff it for very long.

To test that, Gatti used four dogs of different genders and ages. All had lived together in the same outdoor space for most of their lives. To prepare for the test, Gatti soaked up urine from each animal with pieces of cotton. He then placed each piece of cotton into a separate container. Then he set five of the containers randomly on the ground. Four held smelly cotton from each of the dogs, while the fifth held clean cotton. After opening the containers, Gatti released a dog into the area at a time, and timed how long each of them spent sniffing each container.

As he’d suspected, each dog spent much less time sniffing its own urine. Clearly, Gatti says, they passed the smell test. “If they recognize this smell is ‘mine’,” he explains, “then they know what is ‘mine’.” And, he argues if dogs understand the concept of “mine”, then they’re self-aware.