A Sense of Self

A fundamental feature of cognition is the ability to separate self from others, or to recognize oneself as an entity, separate from the environment. This issue of the internal nature of self-representation is difficult to get at experimentally, and really one one approach has been used successfully. This approach uses a mirror and markings.

When your dog or cat walks past a mirror, it may respond to the image in the mirror, but the it does not recognize the image as itself. This can lead to a humorous escalation in play or aggression, depending on the predisposition of your animal. If you put a piece of pet clothing on the dog or cat--a collar, a hat, or a sweater--your pet's perception of the image in the mirror does not change. This clearly differentiates self-awareness in dogs or cats from human self-awareness.

But what about other animals? In chimpanzees, perhaps a few other primates, killer whales, and bottlnose dophins, changing the image in the mirror causes the animal to behave in a way that suggests self-recognition. In chimpanzees, marking the chimp with a spot of paint or dye will cause the chimp to, when viewing the image, touch the marked spot. This suggests that the chimp sees the image in the mirror as itself, and that it can recognize the change in itself by exploring that change. Marine mammals, of course, lack appendages for self-exploration, but at least a few marine mammals show behavioral responses to changed mirror images that suggest self-recognition.

Seyfarth and Cheney (2000) argue that monkeys which fail the mirror test (for example, vervets, baboons, or macaques) still have a sense of "social self" defined by their ability to recognize other members of their social group as individuals, to remember the gender and dominance status of those other animals, and to define their place in the social order accordingly.

de Veer MW, Van den Bos R 1999 A critical review of methodology and interpretation of mirror self-recognition research in nonhuman primates. ANIM BEHAV 58: 459-468

Delfour F, Marten K 2001. Mirror image processing in three marine mammal species: killer whales (Orcinus orca), false killer whales (Pseudorca crassidens) and California sea lions (Zalophus californianus). BEHAVIOURAL PROCESSES 53 (3): 181-190

Gallup GG, Povinelli DJ, Suarez SD, Anderson JR, Lethmate J, Menzel EW 1995 Further reflections on self-recognition in primates. ANIMAL BEHAVIOUR 50: 1525-1532

Kojima S, Izumi A, Ceugniet M 2003 Identification of vocalizers by pant hoots, pant grunts and screams in a chimpanzee. PRIMATES 44 (3): 225-230 (negative for self recognition)

Marino L 2002 Convergence of complex cognitive abilities in cetaceans and primates BRAIN BEHAV EVOLUT 59 (1-2): 21-32

Reiss D, Marino L 2001. Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. P NATL ACAD SCI USA 98 (10): 5937-5942

Seyfarth RM, Cheney DL 2000 Social awareness in monkeys. AMERICAN ZOOLOGIST 40 (6): 902-909

Shillito DJ, Gallup GG, Beck BB 1999. Factors affecting mirror behaviour in western lowland gorillas, Gorilla gorilla. ANIM BEHAV 57: 999-1004 (negative)