The mirror test—sometimes called the mark test, mirror self-recognition (MSR) test, red spot technique, or rouge test—is a behavioral technique developed in 1970 by American psychologist Gordon Gallup Jr. to determine whether an animal possesses the ability of visual self-recognition. In this test, an animal is anesthetized and then marked (e.g. paint or sticker) on an area of the body the animal normally cannot see (e.g. forehead). When the animal recovers from the anesthetic, it is given access to a mirror. If it subsequently touches or examines the mark on its own body, this behavior is interpreted as evidence that the animal recognizes its reflection as an image of itself, rather than another animal. The MSR test has become a standard approach for evaluating physiological and cognitive self-awareness. However, several critiques have been raised that challenge the test's validity. Some studies have questioned Gallup's findings; others have discovered that animals exhibit self-awareness in ways not captured by the test, such as differentiating between their own songs and scents and those of others. More recently, researchers have found evidence suggesting that self-recognition has more to do with experience and learning than innate ability. One study found that macaque monkeys trained with mirrors passed the mirror test.
Method and history The inspiration for the mirror test comes from an anecdote about Charles Darwin and a captive orangutan. While visiting the London Zoo in 1838, Darwin observed an orangutan named Jenny throwing a tantrum after being teased with an apple by her keeper. This started him thinking about the subjective experience of an orangutan. He also watched Jenny gaze into a mirror and noted the possibility that she recognized herself in the reflection. In 1970, Gordon Gallup Jr. experimentally investigated the possibility of self-recognition with two male and two female wild preadolescent chimpanzees (Pan troglodytes), none of which had presumably seen a mirror previously. Each chimpanzee was put into a room by itself for two days. Next, a full-length mirror was placed in the room for a total of 80 hours at periodically decreasing distances. A multitude of behaviors was recorded upon introducing the mirrors to the chimpanzees. Initially, the chimpanzees made threatening gestures at their images, ostensibly seeing their reflections as threatening. Eventually, the chimps used their reflections for self-directed responding behaviors, such as grooming parts of their body previously not observed without a mirror, picking their noses, making faces, and blowing bubbles at their reflections. Gallup expanded the study by manipulating the chimpanzees' appearance and observing their reaction to their reflection in the mirror. Gallup anesthetized the chimps and then painted a red alcohol-soluble dye on the eyebrow ridge and the top half of the opposite ear. When the dye dried, it had virtually no olfactory or tactile cues. Gallup then removed the mirror before returning the chimpanzees to the cage. After regaining full consciousness, he recorded the frequency with which the chimps spontaneously touched the marked areas of skin. After 30 minutes, the mirror was reintroduced into the cage, and the frequency of touching the marked areas was again determined. With the mirror present, the frequency increased from four to ten, compared to only one when the mirror had been removed. The chimpanzees sometimes visually or olfactorily inspected their fingers after touching the marks. Other mark-directed behavior included turning and adjusting the body to better view the mark in the mirror or tactile examination of the mark with an appendage while viewing the mirror. An essential aspect of the classical mark test (or rouge test) is that the mark/dye is nontactile, preventing attention from being drawn to the marking through additional perceptual cues (somesthesis). For this reason, animals in the majority of classical tests are anesthetized. Some tests use a tactile marker. If the creature stares unusually long at the part of its body with the mark or tries to rub it off, then it is said to pass the test. Animals that are considered to be able to recognize themselves in a mirror typically progress through four stages of behavior when facing a mirror:
The rouge test was also done by Michael Lewis and Jeanne Brooks-Gunn in 1979 for the purpose of self-recognition with human mothers and their children.
Implication and alternate explanations The default implication drawn from Gallup's test is that those animals who pass the test possess some form of self-recognition. However, a number of authors have suggested alternative explanations of a pass. For example, Povinelli suggests that the animal may see the reflection as some odd entity that it is able to control through its own movements. When the reflected entity has a mark on it, then the animal can remove the mark or alert the reflected entity to it using its own movements to do so. Critically, this explanation does not assume that the animals necessarily see the reflected entity as "self".
Criticism The MSR test has been criticized for several reasons, in particular because it may result in false negative findings.
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