Many people are puzzled by the fact that dogs seem to ignore images of themselves reflected in a mirror.

Young puppies encountering mirrors for the first time may treat the image as if it is another dog. They may bark at it, or give a little bow and an invitation to play as if they are encountering a real dog and engaging in a social interaction. However, after a short while they lose interest. Afterward, they often seem to treat their reflections as if they were of no consequence at all.

When we humans look into a mirror, we immediately recognize that the image that we are gazing at is our own. It seems so natural that we tend not to think about it is something special, however, psychologists treat this as a major mental feat because it requires self-awareness, which is one of the most sophisticated aspects of consciousness. In effect, we must be able to mentally step outside of ourselves and consider ourselves as separate entities from the rest of the world.

We are not born with the ability to recognize ourselves in mirrors. Young infants may be fascinated by their reflection, however, they view this as a social interaction with what appears to be another baby. Somewhere between the age of 18 and 24 months, babies begin to understand that they are looking at themselves in a mirror.

This was demonstrated by Jeanne Brooks-Gunn and Michael Lewis who surreptitiously placed rouge spots on the baby's face. If the baby thinks that he is looking at another child, or some sort of image, the red spots that he sees evoke little interest.

However, once he understands that he is looking at his own image, he will begin to selectively touch and explore those spots while looking at the mirror, since he now understands that this is a representation of himself.

Gordon Gallup, a psychologist from the State University of New York at Albany, did a similar experiment on chimpanzees.

First, he introduced a mirror into the home cage of a chimpanzee. At first, they reacted as if they were seeing another individual but over time they learned that this was their own reflection.

Next, Gallup anesthetized the chimpanzee and painted a red mark on its eyebrow and another over its ear. When the anesthesia wore off, the chimp failed to show any interest in the marks until it caught sight of itself in the mirror. On seeing its image with the red marks, the chimp began to act like children who know that they are looking at themselves in the mirror, and began to touch their own eyebrow and ear, while carefully watching its image in the mirror.

Gallup believes that this means that the chimp is self-aware. It understands that it is an individual and that the reflection that it is looking at is of himself. Orangutans, gorillas, and dolphins also respond with the same evidence of self-awareness when presented with mirror images of themselves. However, dogs and other species either treat the image as another animal, or come to ignore it completely.

The conclusion that researchers drew from the fact that dogs fail the mark and mirror test is that dogs lack self-awareness, and thus consciousness. Another conclusion that could be drawn, of course, is that dogs recognize that that is their own reflection, but they are simply not as vain and concerned with their appearance as higher primates.

University of Colorado biologist Marc Bekoff had another way of interpreting these apparently negative results. He recognized that dogs are considerably less affected by visual events than are humans and most apes.

Perhaps the difficulty resides with the sensory modality used to test self-awareness in dogs. The most important sense for dogs is not sight, as in primates, but it's smell.

Dogs certainly seem to recognize the of familiar dogs and people, and if they have a sense of self, then perhaps rather than asking them to recognize their own reflection we should ask them to recognize their own scent.

Instead of a "red dot test" for self-awareness, Bekoff used a "yellow snow test." His subject was his own dog, Jethro, a Rottweiler and German shepherd cross. He described the clever, but rather inelegant experimental process this way.

"Over five winters, I walked behind Jethro and scooped up his yellow snow and moved it to different, clean, locations some distance down the trail. I also gathered yellow snow from other dogs and moved it. There is a real advantage to doing this experiment on snow because it holds the urine and is easily portable. It took five winters to get all of the data, so you know that this was a labor of love."

All of this snow moving occurred while Jethro was elsewhere along the path and the dog did not see Bekoff transporting it. The testing was quite simple: Bekoff watched Jethro move down the trail, timed his arrival, measured how long the dog sniffed at the urine patch, and watched what else he did.

As most dog owners could probably have predicted, the dog stopped at each yellow snow patch, sniffed at it, and then usually urinated on top of the yellow snow from other dogs. However, Jethro seemed to recognize his own scent since when he encountered his own urine-stained snow. He sniffed at it for a much shorter time than he did the patches of urine from other dogs, and then left it alone.

Based on this data, Bekoff concluded that we can say that dogs do have some of the same aspects of self-awareness that humans have. According to him, they have a sense of "body-ness" which is the feeling of possessing one's own body and owning the parts of his body, such as "my paw" or "my face."

In addition, dogs have a sense of "mine-ness" which is the sense of what belongs to himself and what belongs to others. This would include the sense of "my territory," "my place," and "my bone."

What this data can not establish is whether dogs have a sense of "I-ness," which, for lack of a more concise way of describing it, is what Tarzan was talking about when he says, "Me Tarzan, you Jane" accompanied with expressive pointing.

The experimental test for that quality of self-awareness in dogs does not yet seem to have been worked out, but using a mirror clearly won't work — since reflected images have no scent and therefore are not real or important enough in the mind of a dog to warrant much .

Copyright SC Psychological Enterprises Ltd. May not be reprinted or reposted without permission.

Stanley Coren is the author of many books, including: Born to Bark, The Modern Dog, Why Do Dogs Have Wet Noses? The Pawprints of History, How Dogs Think and How To Speak Dog.