Mirror self-recognition (MSR) is defined as being able to recognize one’s self in a mirror, as opposed to thinking the image is another individual. Tests of MSR are used to study whether an individual has self-awareness or a “sense of self” and self-concept. MSR in humans has been shown to develop around age two and includes four stages of development (Amsterdam, 1972). MSR is traditionally tested using a mirror mark test (first developed by Gallup, 1970, for use with nonhuman animals). During this test, a mark is placed unknowingly on an individual’s face in a place that can only be seen with a mirror. Behaviors in front of the mirror directed at the self (including mark-directed behaviors) are evidence of mirror self-recognition, as opposed to behaviors directed at the mirror image as if the image was another conspecific (e.g., play behavior). Research in animals with the mark test has shown MSR in several species but not in others. However, there is debate around whether the mark test is the best task for animal research of MSR.

Amsterdam, B. (1972). Mirror self-image reactions before age two. Developmental Psychobiology, 5, 297-305.

Gallup, G. G., Jr. (1970). Chimpanzees: Self-recognition. Science, 167, 86-87.

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