Mirror test

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Example of an experiment: dog looks at itself in the mirror

A mirror test is an experiment in self-perception in which a mirror is brought into the field of vision of a test animal or a test person and the reaction to a feature artificially attached to the body is observed. A typical form of the test is drawing a color mark on a spot that can only be seen by looking in the mirror. This test set-up is used to test whether the individual's behavior indicates that the marking is on their own body.

The mirror test methodology was developed independently by Gordon G. Gallup for chimpanzees (1970) and Beulah Amsterdam for young children (1972). It is controversial about the significance of passing the mirror test, in addition to providing evidence of self-perception, for example for self -awareness in animals.

Mirror test in children

To test children, for example, rouge is applied to their face ( rouge test ). Then it is observed whether the child shows a reaction when looking at their own reflection that suggests that the stain is located on their own body. Such a reaction can be, for example, an attempt to wipe away the stain.

Children consistently pass the mirror test at around 24 months of age; From an age of around 18 months, the mirror test shows that it is recognized. The French psychoanalyst Jacques Lacan called the developmental phase of the child, during which this ability for self-awareness develops, the mirror stage .

A modification of the mirror test is the use of video cameras and monitors with the aim of gaining information about the point in time at which self-awareness was formed. For this purpose, children were filmed playing and these recordings were shown to them, for example, with a time delay of a few minutes. While they were playing, a large sticker was attached to their heads without being noticed . Children two to four years old - but not all - removed the sticker immediately after playing the recording, but younger children did not.

Mirror test in animals

In mirror tests, a distinction must be made between “understanding” how a mirror works and recognizing one's own reflection. Only the latter can be interpreted as passing the mirror test.

A prerequisite for self-perception with the help of the mirror test was observed in a test in young pigs in 2009 : After a short period of acclimatization, they searched relatively quickly and specifically for a feeding trough whose exact position they could only locate using its mirror image. Many dogs can also use a mirror to find hidden food. However, neither pigs, dogs nor cats pass the classic mirror test with a marker. In dogs, this may be because they do not primarily perceive their environment visually.

The passing of the mirror test cannot always be proven beyond doubt. A colored stain on the skin or a colored clip in the fur often cannot be applied unnoticed, or a wiping reaction is not possible (for example with toothed whales ), or such a mark would be removed by members of the social groups. In such cases, one has to do the mirror test without marking and observe whether the behavior is atypical compared to the reaction to a strange individual.

Chinese neurobiologists chose an alternative approach for experiments with three rhesus monkeys that initially failed the mirror test. In several weeks of training, the monkeys were accustomed to correctly point to a light spot projected by a laser pointer , the exact position of which they could only see through a mirror. After they had learned this coupling of visual stimulus and pointing movement, the light spot was projected onto their head for the first time: All three monkeys were now able to identify the reflection of their head as "their own head" and to point to the spot.

Failure to pass the mirror test is expressed in most species by reacting to the mirror image as if it were a strange individual - depending on the species, these can be threatening gestures, warning sounds, greetings or simply ignoring.

Mammals

  • Monkey: The Great Apes pass the mirror test regularly. A more frequent observation, which is often interpreted as self-recognition in monkeys and humans, is the close approach to the mirror with atypical viewing of the teeth, which appears to the observer like violent grimacing .
    • Chimpanzees : Both common chimpanzees and bonobos pass the mirror test. After a short phase with warning sounds (like an individual in a foreign group), the similar behavior is recognized, also through playful tests with throwing the arms around, then stepping up to the mirror and examining the teeth. All of this only applies to monkeys who grew up with social contact; monkeys raised in isolation do not recognize each other.
    • Orangutans : They consistently pass the mirror test. You can then also use a hand mirror well and use it freely. As early as 1838, Charles Darwin described an orangutan that observed itself in a mirror.
    • Gorillas avoid direct eye contact with other gorillas, which makes it difficult to perform a mirror test on them. After getting used to a mirror, gorillas can also pass the mirror test.
    • Rhesus monkeys do not recognize themselves spontaneously in the mirror, but they can learn to recognize themselves.
  • A number of species of toothed whales , particularly dolphins , pass the mirror test.
  • Asian elephant : Three elephants were confronted with their reflection in the New York Bronx Zoo. After unsuccessful contact with the mirror image, one of the animals was finally observed how it led its trunk to a marking that had previously been placed on its head without being noticed.

Birds

A magpie recognizes the mark in front of a mirror and tries to remove it.
  • Magpies - Experiments from the Ruhr University Bochum in 2000 and 2008 report that mirror tests were passed on magpies that had been marked with a colored spot unnoticed: "The result was convincing, the birds' interest only then clearly focused on their own red throat spot when they were across from their reflection in the mirror. […] We do not yet know how many of the components that enable human self-knowledge are realized in the highly developed brain of the Elster. It remains to be seen, however, that magpies in front of the mirror reacted similarly to chimpanzees and orangutans in comparable tests, which were interpreted in these great apes as an indication of self-recognition. "
  • Pigeons - After tests by Epstein, Lanza and Skinner , published in 1981, a passing of the mirror test was reported; the reproducibility of their test arrangements was at times questioned, but confirmed in 2014.
  • Keas - A dissertation published in 2014 reported that Keas recognize themselves in the mirror. Their behavior towards their reflection in the mirror was different than it would be towards any other animal and they reacted to the color markings on their bodies.
  • Ravens and crows - Also in a study by the Ruhr University Bochum, the animals tried to remove an unnoticed red dot.

Cephalopods

fishes

  • According to a specialist article, the cleaner wrasse Labroides dimidiatus passes the test: the animals remove a colored stain if they can see it in the mirror. If the researchers provided the animals with spots but did not give them a mirror, the fish did not react to it, or to transparent markings that were not visible in the mirror. They also do not react to spots directly on the mirror. “With all these observations, we can rule out that the fish react instinctively to markings in their environment that are reminiscent of parasites. Only the sight of spots on its own skin is therefore a stimulus for a cleaner fish to react to. This means that the cleaner fish's behavior meets all the criteria for a passed mirror test, ”argued co-author Alex Jordan from the Max Planck Institute for Ornithology and the University of Konstanz.

See also

literature

  • M. Beckoff, C. Allen, GM Burghardt (Eds.): The Cognitive Animal. Empirical and Theoretical Perspectives on Animal Cognition. The MIT Press, 2002, ISBN 0-262-02514-0 .
  • Thomas Suddendorf and Emma Collier-Baker: The evolution of primate visual self-recognition: evidence of absence in lesser apes. In: Proceedings of the Royal Society B. Volume 276, 2009, pp. 1671-1677, doi: 10.1098 / rspb.2008.1754
  • Philippe Rochat and Dan Zahavi : The Eerie Mirror. A reassessment of the mirror self-awareness experiments as a test for the existence of conceptual self-awareness. In: German magazine for philosophy. Volume 62, No. 5, 2014, pp. 913-936, doi: 10.1515 / dzph-2014-0060

Web links

Individual evidence

  1. ↑ a b Gordon G. Gallup, Jr .: Chimpanzees: Self-Recognition. In: Science . Volume 167, No. 3914, 1970, pp. 86 f., Doi: 10.1126 / science.167.3914.86 .
  2. ↑ a b Beulah Amsterdam: Mirror self-image reactions before age two. In: Developmental Psychobiology. Volume 5, No. 4, 1972, pp. 297-305, doi: 10.1002 / dev.420050403
  3. ↑ Kim A. Bard et al .: Self-Awareness in Human and Chimpanzee Infants: What Is Measured and What Is Meant by the Mark and Mirror Test? In: Infancy. Volume 9, No. 2, 2006, pp. 191-219, doi: 10.1207 / s15327078in0902_6
  4. ↑ Mark Nielsen, Thomas Suddendorf, and Virginia Slaughter: Mirror Self-Recognition Beyond the Face. In: Child Development. Volume 77, No. 1, 2006, pp. 176-185, doi: 10.1111 / j.1467-8624.2006.00863.x , full text
  5. ^ Daniel J. Povinelli, Keli R. Landau and Helen K. Perilloux: Self-Recognition in Young Children Using Delayed versus Live Feedback: Evidence of a Developmental Asynchrony. In: Child Development. Volume 67, No. 4, 1996, pp. 1540-1554, doi: 10.2307 / 1131717
  6. ↑ Tobias Rahde: Levels of mental representation in Keas (Nestor notabilis). (Dissertation) 2014. p. 53. ( Online )
  7. ↑ Donald Broom et al .: Pigs learn what a mirror image represents and use it to obtain information. In: Animal Behavior. Volume 78, No. 5, 2009, pp. 1037-1041, doi: 10.1016 / j.anbehav.2009.07.027 . See pigs can recognize themselves in the mirror . In: welt.de , November 10, 2009. In the original work, however, there is no talk of “self-awareness”, but rather of assessment awareness (analogously: “evaluation of perception”).
  8. ↑ Tiffani J. Howell, Samia Toukhsati et al. a .: Do dogs use a mirror to find hidden food? In: Journal of Veterinary Behavior: Clinical Applications and Research. 8, 2013, pp. 425-430, doi: 10.1016 / j.jveb.2013.07.002 .
  9. ↑ Alexandra Binder: Even those who do not recognize themselves in the mirror can be self-aware. In: Vet-Journal. 02/2014, pp. 46-49. ( Online ( Memento from July 14, 2014 in the Internet Archive ))
  10. ^ Robert W. Mitchell: Evidence of Dolphin Self-Recognition and the Difficulties of Interpretation. In: Consciousness and Cognition. Volume 4, No. 2, 1995, pp. 229-234, doi: 10.1006 / ccog.1995.1029
  11. ↑ Liangtang Chang et al .: Spontaneous expression of mirror self-recognition in monkeys after learning precise visual-proprioceptive association for mirror images. In: PNAS. Online advance publication of February 13, 2017, doi: 10.1073 / pnas.1620764114
  12. ^ GG Gallup: Self-recognition in primates: A comparative approach to the bidirectional properties of consciousness. In: American Psychologist . Volume 32, No. 5, 1977, pp. 329-338, doi: 10.1037 / 0003-066X.32.5.329 .
  13. ↑ Vera Walraven, Linda van Elsacker and Rudolf Verheyen: Reactions of a group of pygmy chimpanzees (Pan paniscus) to their mirror-images: Evidence of self-recognition. In: Primates. Volume 36, No. 1, 1995, pp. 145-150, doi: 101007 / BF02381922
  14. ↑ Susan D. Suarez and Gordon G. Gallup Jr .: Self-recognition in chimpanzees and orangutans, but not gorillas. In: Journal of Human Evolution. Volume 10, No. 2, 1981, pp. 175-188, doi: 10.1016 / S0047-2484 (81) 80016-4
  15. ^ Zoological Society of London: Artefact of the month: Portrait of Jenny. On: zsl.org from June 1, 2008
  16. ↑ Sandra Posada and Montserat Colell: Another gorilla (Gorilla gorilla gorilla) recognizes himself in a mirror. In: American Journal of Primatology. Volume 69, No. 5, 2007, pp. 576-583, doi: 10.1002 / ajp.20355
  17. ↑ Liangtang Chang et al .: Mirror-Induced Self-Directed Behaviors in Rhesus Monkeys after Visual Somatosensory training. In: Current Biology. Volume 25, No. 2, 2015, pp. 212–217, doi: 10.1016 / j.cub.2014.11.016
    Monkeys can learn to see themselves in the mirror. On: eurekalert.org from January 8, 2015 (with video of the test arrangement)
  18. ^ Diana Reiss, Lori Marino: Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence. In: PNAS . Volume 98, No. 10, 2001, pp. 5937-5942, doi: 10.1073 / pnas.101086398 .
  19. ↑ Joshua M. Plotnik, Frans de Waal , Diana Reiss: Self-recognition in an Asian elephant. In: PNAS. Volume 103, No. 45, 2006, pp. 17053-17057, doi: 10.1073 / pnas.0608062103 .
  20. ↑ H. Prior, B. Pollok, O. Güntürkün : Self vis-à-vis: What magpies perceive . In: ruby . No. 2 , 2000, pp. 26–30 (on this an article by the Ruhr University Bochum ( archive version from July 24, 2001 )). See H. Prior, A. Schwarz, O. Güntürkün: Mirror-Induced Behavior in the Magpie ( Pica pica ): Evidence of Self-Recognition . In: PLoS Biology . tape 6 , no. 8 , 2008, p. e202 , doi : 10.1371 / journal.pbio.0060202 .
  21. ^ Robert Epstein, Robert P. Lanza, BF Skinner: "Self-Awareness" in the Pigeon . In: Science . tape 212 , no. 4495 , April 8, 1981, pp. 695 f ., doi : 10.1126 / science.212.4495.695 .
  22. ↑ Emiko Uchino and Shigeru Watanabe: Self-recognition in pigeons revisited. In: Journal of the Experimental Analysis of Behavior. Volume 102, No. 3, 2014, pp. 327–334, doi: 10.1002 / jeab.112
  23. ↑ Tobias Rahde: Levels of mental representation in Keas (Nestor notabilis). (Dissertation) 2014. pp. 100–128. ( Online )
  24. ↑ Lindsay Jordan, "What Lurks Beneath the Depths: Does Cephalopod Consciousness Exist?" (English), accessed February 26, 2016
  25. ↑ Jennifer A. Mather and Michael J. Kuba: The cephalopod specialties: complex nervous system, learning, and cognition. In: Canadian Journal of Zoology. Volume 91, No. 6, 2013, pp. 431–449, full text ( Memento from December 3, 2018 in the Internet Archive )
  26. ↑ Masanori Kohda et al .: Cleaner wrasse pass the mark test. What are the implications for consciousness and self-awareness testing in animals? In: bioRxiv. August 21, 2018, doi: 10.1101 / 397067 , bioRxiv : 2018/08/21/397067 ( Preprint - full text) (= preliminary information on a planned contribution in PLoS Biology ).
  27. ↑ Are fish aware of themselves? On: idw-online.de from February 7, 2019