Mirror test

The mirror test is a measure of self awareness developed by Gordon G. Gallup.

The test gauges self awareness by determining whether an animal can recognize its own reflection in a mirror as an image of itself. This is accomplished by surreptitiously marking the animal with a odourless dye, and observing whether the animal reacts in a manner consistent with it being aware that the dye is located on its own body. Such behaviour might include turning and adjusting of the body in order to better view the marking in the mirror, or poking at the marking on its own body with a finger while viewing the mirror.

Animals which have passed the mirror test are chimpanzees, orangutans, dolphins, and humans. Surprisingly, gorillas have not passed the test, although at least one specific gorilla, Koko, has passed the test. Human children tend to fail this test until they are at least 3–4 years old. Dogs and 2 year old children, for example, usually react to a mirror in fear or curiosity, or simply ignore it.

There is some debate in the scientific community as to the value and interpretation of results of the mirror test. While this test has been extensively conducted on primates, there is also debate as to the value of the test as applied to animals who rely primarily on senses other than vision, such as dogs.