The mirror test of self-awareness: what it is and how it is used in animals

This psychological test is used to see if animals can have a concept of "Self".

Since time immemorial, anthropocentrism has led us to think that human beings are the only species capable of recognizing themselves and having self-awareness. However, research has been showing that this is not the case and that many other animals, such as dolphins, orangutans or elephants, could have this same capacity.

To study this phenomenon, the mirror test has been used, a test that, until now, has been used to measure self-recognition or self-awareness in animals. And we say so far because in recent years, with the discovery that even ants or fish pass the test, part of the scientific community has questioned the validity of the test to measure this cognitive ability.

In this article we explain what the Self-Awareness Mirror Test consists of and what are its limitations. In addition, we review the latest research on this interesting phenomenon.

The self-awareness mirror test: what is it and what is it for?

The mirror test, developed in 1970 by Gordon G. Gallup Jr, is a test that measures the level of self-awareness and visual self-recognition. What the test determines is whether an animal can recognize its own reflection in a mirror as if it were an image of itself..

This test is quite simple: just place a mirror at the animal's disposal and observe its behavior. When the animal becomes accustomed to the mirror, the researchers mark with an odorless dye a part of its body that cannot be seen without the aid of the mirror. Thus, if the animal reacts in a manner consistent with being aware that the dye is in its own body, positive evidence of self-awareness is obtained..

Behaviors that indicate that the animal is able to recognize itself in its mirror image include turning and adjusting the body to better see the mark in the mirror, or touching the mark with its own body or with a finger while looking in the mirror. Animals that until recently have passed the mirror test have included: chimpanzees, bonobos, orangutans, dolphins, elephants, common pigeons and, of course, humans.

However, recent research has found that even some species of ants and fish even some species of ants and fish have reacted positively to the self-awareness mirror test.This has generated great controversy in the scientific community, dividing opinion between those who believe that the test is neither valid nor conclusive and those who believe that the implications it may have for the study of human self-awareness should be reconsidered.

Research with wrasse

One of the studies that has revolutionized the field of animal self-awareness research has been the research of Kohda et al. (2019) in which the behavior of a fish of the labrid family was observed under the conditions of the mirror test..

The results of the study concluded that the fish reacted to its reflection when observed in the mirror and met all the criteria of the mirror test. However, when the fish was provided with a colored label in a modified mark test, the animal attempted to remove the mark by scratching its body in the presence of the mirror, but showed no response to the transparent or colored marks in the absence of the mirror.

For the authors of the study, although the wrasse shows behavioral responses that meet the test criteria established for other animals, the result does not imply that this species is self-conscious.. Nevertheless, the results of this research raise several questions that remain to be answered: is this test really valid for detecting self-awareness in animals? And if so, if this species of fish is self-aware, should we rethink the concept?

Does the mirror test really measure self-awareness?

The validity of a test such as the mirror test had not been seriously discussed until the publication of new research with animal species that, a priori, we would never have thought capable of showing signs of self-awareness. The positive evidence in fish and ants has forced much of the scientific community to raise doubts as to whether the mirror test is a good measure of self-awareness.

Alex Jordan, an evolutionary biologist and one of the authors of the controversial study in wrasse, is reluctant to say that fish are as intelligent as chimpanzees or 20-month-old human babies, and questions the validity of the mirror test for measuring the concept of self-awareness.

According to Jordan, one of the problems with the test is that vision is used to measure self-awareness. However, not all animals (or all humans) rely on sight as the predominant sense.. For example, it is possible that bats, which rely on their sonar to move around, are self-aware and we simply are not able, as humans, to formulate a test that detects this because of our visual bias.

Similarly, although elephants can pass the mirror test, they rely more on smell than sight, and the sophistication of their awareness may have led us to misleading interpretations. In this sense, it is possible that this test is simply not suitable for some animals, because we do not have the same sensory view of the world.

• You may be interested in "Do two consciousnesses appear when the brain is split?"

The "smell" mirror test

To overcome the visual bias of the self-awareness mirror test, Horowitz et al. (2017) designed a sniff test for dogs that involved altering the odor of their urine. It should be noted that these animals failed the traditional test, as they are not able to recognize themselves in the mirror.

In the experiment, the researchers presented the dogs with several containers. Each of them contained an olfactory stimulus: in one, the dog's own urine; and in the other, a urine whose odor had been altered. By observing the time each dog spent in the containers, it was found that they were able to distinguish between the two, it was found that they were able to distinguish between the olfactory "image" of themselves and the altered one.They tracked their own odor longer when it had an additional odor accompanying it than when it did not.

The ecological validity of the olfactory test was examined by presenting subjects with odors of other known or unknown dogs: the dogs spent more time investigating the odor of other canids than their own odor. Finally, in a second experiment, the dogs spent more time with the modified stimulus than with the modified odor alone, indicating that novelty alone did not explain their behavior.

Ultimately, the results of this research suggest that the dogs' behavior involves some recognition of their own odor, which translated to the odor testwhich translated into the traditional self-awareness mirror test implies the existence of visual self-recognition or "self-awareness" in these animals. Something that should come as no surprise to all those who live with these domestic creatures.

Bibliographical references:

• Bard, K. A., Todd, B. K., Bernier, C., Love, J., & Leavens, D. A. (2006). Self‐awareness in human and chimpanzee infants: What is measured and what is meant by the mark and mirror test?. Infancy, 9(2), pp. 191 - 219.
• Horowitz, A. (2017). Smelling themselves: Dogs investigate their own odours longer when modified in an “olfactory mirror” test. Behavioural processes, 143, pp. 17 - 24.
• Kohda, M., Hotta, T., Takeyama, T., Awata, S., Tanaka, H., Asai, J. Y., & Jordan, A. L. (2019). If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals?. PLoS biology, 17(2), e3000021.