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Mirror test

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The mirror test is a measure of self-awareness, as animals either possess or lack the ability to recognize themselves in a mirror.

The test was developed by Gordon Gallup Jr. in 1970,[1][2] based in part on observations made by Charles Darwin.[3][4] While visiting a zoo, Darwin held a mirror up to an orangutan and recorded the animal's reaction, which included making a series of facial expressions. Darwin noted that the significance of these expressions was ambiguous, and could either signify that the primate was making expressions at what it perceived to be another animal, or it could be playing a sort of game with a new toy.

Gallup built on these observations by devising a test that attempts to gauge 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 two odourless dye spots. The test spot is on a part of the animal that would be visible in front of a mirror, while the control spot is in an accessible but hidden part of the animal's body. Scientists observe that the animal reacts in a manner consistent with it being aware that the test dye is located on its own body while ignoring the control dye. Such behaviour includes 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 limb while viewing the mirror.

At first, even animals that are capable of passing the mirror test respond as the orangutan described by Darwin.[4] In fact, young children and people who have been blind from birth but have their sight restored, initially react as if their reflection in the mirror was another person.[3][4]

Animals that have been observed to pass

The European Magpie passes the test

Animals that have passed the mirror test include:

Initially, it was thought that gorillas did not pass the test, but there are now several well-documented reports of gorillas (such as Koko[12]) passing the test. Other primates have so far failed the mirror test, though rhesus macaques demonstrated a behavior indicative of at least a partial self-awareness.[13]. There is also a barn owl named Wesley that can recognize itself in the mirror [14]

Humans tend to fail the mirror test until they are about 18 months old, or what psychoanalysts call the "mirror stage".[15][3][4]

Animals that only pass different versions of the test or other tests involving mirrors

In 1981, Epstein, Lanza and Skinner published a paper in the journal Science in which they argued that the pigeon also passes the mirror test.[16][17] A pigeon was trained to look in a mirror to find a response key behind it which the pigeon then turned to peck - food was the consequence of a correct choice (i.e., the pigeon learned to use a mirror to find critical elements of its environment). Next, the pigeon was trained to peck at dots placed on its feathers; food was, again, the consequence of touching the dot. The latter training was accomplished in the absence of the mirror. The final test was placing a small bib on the pigeon - enough to cover a dot placed on its lower belly. A control period without the mirror present yielded no pecking at the dot. When the mirror was revealed, the pigeon became active, looked in the mirror and then tried to peck on the dot under the bib. It is true that untrained pigeons have never been able to pass the mirror test.[18] However, pigeons do not normally have access to mirrors and do not have the necessary experiences to use them. Giving the pigeons this experience did not guarantee that they would pass the mirror test; the pigeon never pecked dots on its own body in the presence of the mirror (until the final test).

Capuchin monkeys react to their reflection either with hostility or affection, and mark test experiments have shown that they are incapable of spontaneous mirror self-recognition.[19] Similar tests performed using video technology support these findings, but suggest that the monkeys possess the raw input systems required for explicit self-recognition.[20]

Pigs are able to the use information seen in a mirror but do not show evidence of self-recognition. In an experiment, 7 of the 8 pigs tested were able to find a bowl of food hidden behind a wall using a mirror. The eighth pig looked behind the mirror for the food.[21]

Discussion

There is some debate as to the value and interpretation of results of the mirror test.[3] While this test has been extensively conducted on primates, there is debate as to the value of the test as applied to animals who rely primarily on senses other than vision.[3][verification needed] Adaptations of the mirror test have been made in other modalities, such as scent. For instance, biologist Marc Bekoff developed a paradigm using dog urine for testing self-awareness in canines.[3][4]

Proponents[who?] of the hard problem of consciousness claim that the mirror test only demonstrates that some animals possess a particular cognitive capacity for modeling their environment, but not for the presence of phenomenal consciousness per se.[citation needed] Granting consciousness to animals might require demonstrations of thought-directed self-awareness, such as metacognition.

Some critics, such as philosopher Stuart Smith, maintain that it does not establish the existence of self-awareness of an independent character in animals whose self-awareness is solely a product of external experience.[citation needed]

Furthermore, even visually oriented creatures may not be familiar enough with mirrors to pass the test, or may not be motivated to touch a mark on their forehead for any number of reasons. Thus, Gallup's mirror test has been criticized as logically invalid because negative results are uninterpretable. Prosopagnosiacs, for example, may fail the test despite having the ability to report self awareness.[citation needed]

See also

References

  1. ^ Gallup, GG Jr. (1970). "Chimpanzees: Self recognition". Science. 167 (3914): 86–87. doi:10.1126/science.167.3914.86. PMID 4982211.
  2. ^ Psychologist May 1977
  3. ^ a b c d e f Stanley Coren. How dogs think. ISBN 0743222326.
  4. ^ a b c d e Archer, John (1992). Ethology and Human Development. Rowman & Littlefield. ISBN 0389209961.
  5. ^ a b Miller, Jason (2009). "Minding the Animals: Ethology and the Obsolescence of Left Humanism". American Chronicle. Retrieved 21 May 2009.
  6. ^ Povinelli, Daniel (2003). "An 8-year longitudinal study of mirror self-recognition in chimpanzees (Pan troglodytes)". Neuropsychologia. 41 (2): 229–334. doi:10.1016/S0028-3932(02)00153-7. ISSN 0028-3932. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  7. ^ "National Geographic documentary "Human Ape"". Retrieved 11 June 2010.
  8. ^ Marten, K. & Psarakos, S. (1995). "Evidence of self-awareness in the bottlenose dolphin (Tursiops truncatus)". In Parker, S.T., Mitchell, R. & Boccia, M. (ed.). Self-awareness in Animals and Humans: Developmental Perspectives. Cambridge University Press. pp. 361–379. Retrieved 4 October 2008.{{cite book}}: CS1 maint: multiple names: authors list (link)
  9. ^ "Mirror image processing in three marine mammal species: killer whales (Orcinus orca), false killer whales (Pseudorca crassidens) and California sea lions (Zalophus californianus)". PMID 11334706. {{cite journal}}: Cite journal requires |journal= (help)
  10. ^ Joshua M. Plotnik, Frans B.M. de Waal, and Diana Reiss (2006) Self-recognition in an Asian elephant. Proceedings of the National Academy of Sciences 103(45):17053–17057 10.1073/pnas.0608062103 abstract
  11. ^ Prior, Helmut; Schwarz, Ariane; Güntürkün, Onur; De Waal, Frans (2008). "Mirror-Induced Behavior in the Magpie (Pica pica): Evidence of Self-Recognition" (PDF). PLoS Biology. 6 (8). Public Library of Science: e202. doi:10.1371/journal.pbio.0060202. PMC 2517622. PMID 18715117. Retrieved 21 August 2008.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  12. ^ Francine Patterson and Wendy Gordon The Case for Personhood of Gorillas. In The Great Ape Project, ed. Paola Cavalieri and Peter Singer, St. Martin's Griffin, 1993, pp. 58–77.
  13. ^ Keim, Brandon (2010). "Monkeys See Selves in Mirror, Open a Barrel of Questions". Wired. Retrieved 1 October 2010.
  14. ^ http://books.google.com/books?id=g9U-1xxjxAsC&printsec=frontcover&dq=wesley+the+owl&hl=en&src=bmrr&ei=l-x0TvuENaPniALQv7S0Ag&sa=X&oi=book_result&ct=result&resnum=1&ved=0CEAQ6AEwAA#v=onepage&q=mirror&f=false
  15. ^ "Consciousness and the Symbolic Universe"
  16. ^ Epstein, Lanza; Skinner, RP; Skinner, BF (1981). ""Self-awareness" in the pigeon". Science. 212 (4495): 695–696. doi:10.1126/science.212.4495.695. PMID 17739404.
  17. ^ http://psychology.lafayette.edu/files/2010/06/selfaware.mov is video of one such test
  18. ^ Frans B.M. de Waal. "The Thief in the Mirror" (PDF). PLoS Biology. Public Library of Science. Retrieved 6 January 2009.
  19. ^ Roma, Peter (25 January 2007). "Mark tests for mirror self-recognition in capuchin monkeys (Cebus Apella) trained to touch marks". American Journal of Primatology. 69 (9): 989–1000. doi:10.1002/ajp.20404. ISSN 0275-2565. PMID 17253635. The results are consistent with the finding that no monkey species is capable of spontaneous mirror self-recognition. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  20. ^ Anderson, James (24 June 2008). "Capuchin monkeys (Cebus apella) respond to video images of themselves". Animal Cognition. 12 (1): 55–62. doi:10.1007/s10071-008-0170-3. ISSN 1435-9448. PMID 18574604. Although they showed no signs of explicit self-recognition, the monkeys' behaviour strongly suggests recognition of the correspondence between kinaesthetic information and external visual effects. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  21. ^ http://dx.doi.org/10.1016/j.anbehav.2009.07.027

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