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{{Short description|Animal self-awareness test}}
{{Use dmy dates|date=December 2021}}
[[File:Mirror test with a Baboon.JPG|thumb|The [[hamadryas baboon]] is one of many primate species that has been administered the mirror test.|alt=]]
The '''mirror test'''—sometimes called the '''mark test''', '''mirror self-recognition''' ('''MSR''') '''test''', '''red spot technique''', or '''rouge test'''—is a [[animal behavior|behavioral]] technique developed in 1970 by American psychologist [[Gordon G. Gallup|Gordon Gallup Jr.]] to determine whether an animal possesses the ability of visual self-recognition.<ref name="Gallup">{{cite journal
| author = Gallup, GG Jr.
| title = Chimpanzees: Self recognition
| journal = Science
| volume = 167
| pages = 86–87
| year = 1970
| doi = 10.1126/science.167.3914.86
| pmid = 4982211 
| issue = 3914 
| bibcode = 1970Sci...167...86G
| s2cid = 145295899
}}</ref>  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 the animal then touches or investigates the mark on itself, it is taken as an indication that the animal perceives the reflected image as an image of itself, rather than of another animal.

The MSR test became the traditional method for measuring physiological and cognitive [[self-awareness]]. Very few species passed it. However, several critiques have emerged that call into question the value of Gallup's test.<ref name=":1">Swartz, Karyl; Evans, Sian. "Anthropomorphism, Anecdotes, and Mirrors" in Mitchell, Robert; Thompson, Nicholas; and Miles, Lyn ''Anthropomorphism, Anecdotes, and Animals.'' New York: State University of New York Press (1997). pp 296-310.</ref><ref>{{Cite news |last=Crair |first=Ben |date=April 14, 2023 |title=The Mirror Test Is Broken |url=https://www.theatlantic.com/science/archive/2023/04/fish-mirrors-animal-cognition-self-awareness-science/673718/ |access-date=January 27, 2025 |work=The Atlantic}}</ref> Studies have challenged Gallup's results;<ref name=":1" /> others have found that animals can be self-aware in ways not measured by the test, such as distinguishing between their own and others' [[Hearing|songs]] and [[Sense of smell|scents]].<ref name="bekoff">{{Cite journal |last=Bekoff |first=Marc |date=2002-09-19 |title=Animal reflections |journal=Nature |volume=419 |issue=6904 |pages=255 |doi=10.1038/419255a |pmid=12239547 |s2cid=10070614 |doi-access=free }}</ref>

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==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.<ref name="darwin1">{{cite magazine|first=Jonathan|last=Weiner|title=Darwin at the Zoo|url=http://www.scientificamerican.com/article.cfm?id=darwin-at-the-zoo|date=1 December 2006|magazine=[[Scientific American]]}}</ref> He also watched Jenny gaze into a mirror and noted the possibility that she recognized herself in the reflection.<ref name="darwin2">Carl Zimmer. ''The Descent of Man: The Concise Edition.'' excerpt available at [http://carlzimmer.com/books/descentofman/excerpt.html http://carlzimmer.com/books/descentofman/excerpt.html] {{Webarchive|url=https://web.archive.org/web/20080229004750/http://carlzimmer.com/books/descentofman/excerpt.html |date=29 February 2008 }}.</ref>

In 1970, Gordon Gallup Jr. experimentally investigated the possibility of self-recognition with two male and two female wild preadolescent [[chimpanzee]]s (''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.<ref name="Gallup" />

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.<ref name="Mitchell">{{cite journal|author=Mitchell, R.W.|year=1995|title=Evidence of dolphin self-recognition and the difficulties of interpretation|journal=Consciousness and Cognition|volume=4|issue=2|pages=229–234|doi=10.1006/ccog.1995.1029|pmid=8521261|s2cid=45507064}}</ref> 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:<ref name="Plotnik2006" />
{{ordered list|list_style_type=lower-alpha
| social responses
| physical inspection (e.g., looking behind the mirror)
| repetitive mirror-testing behavior
| realization of seeing themselves}}

The rouge test was also done by [[Michael Lewis (psychologist)|Michael Lewis]] and [[Jeanne Brooks-Gunn]] in 1979 for the purpose of self-recognition with human mothers and their children.<ref>{{Cite book|title=Social and Personality Development |last=Shaffer |first=David |publisher=Thomson Wadsworth |year=2009 |isbn=978-0-495-60038-1 |location=Belmont |pages=172}}</ref>

== 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<ref>Povinelli, D. J. (2000). ''Folk physics for apes. The chimpanzee’s theory of how the world works''. Oxford: Oxford University Press.</ref> 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.<ref name="Suddendorf" />

===Perception===
It may be of limited value when applied to species that primarily use senses other than vision.<ref name="coren" /><ref name="bekoff" /><ref>{{cite book |last1=Gibson |first1=Johanna |title=Owned, An Ethological Jurisprudence of Property: From the Cave to the Commons |date=6 December 2019 |publisher=Routledge |isbn=978-1-000-02720-4 |url=https://books.google.com/books?id=rZ7BDwAAQBAJ&dq=Mirror+test+senses+other+than+vision&pg=PT155 |language=en}}</ref> Humans have been determined by [[biologist]]s to have some of the best eyesight amongst animals, exceeding the overwhelming majority in daylight settings, though a few species have better.<ref>{{Cite web |last=Renner |first=Ben |date=2019-01-09 |title=Which species, including humans, has the sharpest vision? Study debunks old beliefs |url=https://studyfinds.org/which-species-greatest-vision-study-debunks-old-beleifs/ |access-date=2024-02-25 |website=Study Finds |language=en-US}}</ref> By contrast, dogs for example mainly use [[Sense of smell|smell]] and [[hearing]]; vision is used third. This may be why dogs fail the MSR test. With this in mind, biologist [[Marc Bekoff]] developed a scent-based paradigm using [[dog urine]] to test self-recognition in canines.<ref name="archer" /><ref name="coren" /> He tested his own dog, but his results were inconclusive.<ref>{{Cite web|last=Coren|first=Stanley|date=7 July 2011|title=Does My Dog Recognize Himself in a Mirror?|url=http://www.psychologytoday.com/blog/canine-corner/201107/does-my-dog-recognize-himself-in-mirror|work=[[Psychology Today]]}}</ref> Dog cognition researcher [[Alexandra Horowitz]] formalized Bekoff's idea in a controlled experiment, first reported in 2016<ref name="Horowitz">{{Cite book|last=Horowitz|first=Alexandra|title=Being a dog : following the dog into a world of smell|date=2016|publisher=Scribner|isbn=9781476795997|location=New York|oclc=955777362}}</ref> and published in 2017.<ref>{{Cite journal|last=Horowitz|first=Alexandra|date=2017|title=Smelling themselves: Dogs investigate their own odors longer when modified in an "olfactory mirror" test|journal=Behavioural Processes|volume=143C|pages=17–24|doi=10.1016/j.beproc.2017.08.001|pmid=28797909|s2cid=4929863}}</ref> She compared the dogs' behavior when examining their own and others' odors, and also when examining their own odor with an added smell "mark" analogous to the visual mark in MSR tests. These subjects not only discriminated their own odor from that of other dogs, as Bekoff had found, but also spent more time investigating their own odor "image" when it was modified, as subjects who pass the MSR test do.<ref name="the atlantic">{{cite web|date=17 August 2017|title=Can Dogs Smell Their 'Reflections'?|url=https://www.theatlantic.com/science/archive/2017/08/can-dogs-smell-their-reflections/537219/|access-date=4 July 2018|website=[[The Atlantic]]}}</ref> A 2016 study suggested an ethological approach, the "Sniff test of self-recognition (STSR)" which did not shed light on different ways of checking for self-recognition.<ref>{{Cite journal|last=Cazzolla Gatti|first=Roberto|date=2016|title=Self-consciousness: beyond the looking-glass and what dogs found there|journal=Ethology Ecology & Evolution|volume=28|issue=2|pages=232–240|doi=10.1080/03949370.2015.1102777|s2cid=217507938}}</ref> Dogs also show self-awareness in the size and movement of their bodies.<ref>{{Cite web |last1=Magazine |first1=Smithsonian |last2=Gamillo |first2=Elizabeth |title=Dogs May Be More Self-Aware Than Experts Thought |url=https://www.smithsonianmag.com/smart-news/canines-may-have-more-self-awareness-how-their-paws-take-space-180977081/ |access-date=2024-02-25 |website=Smithsonian Magazine |language=en}}</ref> Garter snakes, a relatively social snake species, have also passed an odor based "mirror" test.<ref>{{Cite journal |last1=Freiburger |first1=Troy |last2=Miller |first2=Noam |last3=Skinner |first3=Morgan |date=2024-04-10 |title=Olfactory self-recognition in two species of snake |journal=Proceedings of the Royal Society B: Biological Sciences |language=en |volume=291 |issue=2020 |doi=10.1098/rspb.2024.0125 |issn=0962-8452 |pmc=10987230 |pmid=38565155}}</ref>

===Social motivation===
Another concern with the MSR test is that some species quickly respond aggressively to their mirror reflection as if it were a threatening conspecific, thereby preventing the animal from calmly considering what the reflection actually represents. This may be why monkeys fail the MSR test.<ref name="Couchman">{{cite journal|author=Couchman, J.J.|year=2011|title=Self-agency in rhesus monkeys|journal=Biology Letters|volume=8|issue=1|pages=39–41|doi=10.1098/rsbl.2011.0536|pmc=3259954|pmid=21733868}}</ref><ref name="Anderson">{{cite journal|author=Anderson, J.R.|year=1984|title=Monkeys with mirrors: Some questions for primate psychology|journal=International Journal of Primatology|volume=5|issue=1|pages=81–98|doi=10.1007/bf02735149|s2cid=30888917}}</ref>

===Disinterest===
In an MSR test, animals may not recognise the mark as abnormal, or may not be sufficiently motivated to react to it. However, this does not mean they are unable to recognize themselves. For example, in an MSR test conducted on three elephants, only one elephant passed the test, but the two elephants that failed still demonstrated behaviors that can be interpreted as self-recognition. The researchers commented that the elephants might not have touched the mark because it was not important enough to them.<ref name="scientificamerican1">{{cite web|last=Koerth-Baker|first=Maggie|date=29 November 2010|title=Kids (and animals) who fail classic mirror tests may still have sense of self|url=http://www.scientificamerican.com/article.cfm?id=kids-and-animals-who-fail-classic-mirror|access-date=30 May 2013|work=[[Scientific American]]}}</ref> Similarly, lesser apes infrequently engage in self-grooming, which may explain their failure to touch a mark on their heads in the mirror test.<ref name="Suddendorf" /> In response to the question of the subject's motivation to clean, another study modified the test by introducing child subjects to a doll with a rouge spot under its eye and asking the child to help clean the doll. After establishing that the mark was abnormal and to be cleaned, the doll was put away and the test continued. This modification increased the number of self-recognisers.<ref name="Asendorpf">{{cite journal |doi=10.1037/0012-1649.32.2.313 |last1=Asendorpf |first1=J. B. |last2= Warkentin|first2=V. |last3=Baudonniere|first3=P. |title=Self-awareness and other-awareness II: Mirror self-recognition, social contingency awareness, and synchronic imitation |journal=Developmental Psychology |volume=32 |pages=313–321 |year=1996 |issue=2 |s2cid=21762291 |citeseerx=10.1.1.524.8664 }}</ref>

===Ambiguity===
[[Frans de Waal]], a biologist and primatologist at Emory University, has stated that self-awareness is not binary, and the mirror test should not be relied upon as a sole indicator of self-awareness, though it is a good test to have. Different animals adapt to the mirror in different ways.<ref>{{Cite magazine|last=Wilke|first=Carolyn|date=21 February 2019|title=The Mirror Test Peers into the Workings of Animal Minds|url=https://www.the-scientist.com/news-opinion/the-mirror-test-peers-into-the-workings-of-animal-minds-65497|magazine=[[The Scientist (magazine)|The Scientist]]}}</ref>

==Non-human animals==
[[File:Pica pica -Manchester -England -side-8.jpg|thumb|[[European magpie]]s have demonstrated mirror self-recognition.]]

Several studies using a wide range of species have investigated the occurrence of spontaneous, mark-directed behavior when given a mirror, as originally proposed by Gallup. Most marked animals given a mirror initially respond with social behavior, such as aggressive displays, and continue to do so during repeated testing. Only a few species have touched or directed behavior toward the mark, thereby passing the classic MSR test.

Findings in MSR studies are not always conclusive. Even in chimpanzees, the species most studied and with the most convincing findings, clear-cut evidence of self-recognition is not obtained in all individuals tested.<ref name="Prior" /> Prevalence is about 75% in young adults and considerably less in young and aging individuals.<ref name="Povinelli">{{cite journal|last1=Povinelli|first1=D.J.|last2=Rulf|first2=A.B.|last3=Landau|first3=K.R.|last4=Bierschwale|first4=D.T.|year=1993|title=Self-recognition in chimpanzees (Pan troglodytes): distribution, ontogeny, and patterns of emergence|journal=J. Comp. Psychol.|volume=107|issue=4|pages=347–372|doi=10.1037/0735-7036.107.4.347|pmid=8112048}}</ref>

Until the 2008 study on magpies, self-recognition was thought to reside in the [[neocortex]] area of the brain. However, this brain region is absent in nonmammals. Self-recognition may be a case of [[convergent evolution]], where similar evolutionary pressures result in similar behaviors or traits, although species arrive at them by different routes, and the underlying mechanism may be different.<ref name="Suddendorf" />

=== Animals that have passed ===

==== Mammals ====

===== Cetaceans =====
* [[Bottlenose dolphin]] (''Tursiops truncatus''): Researchers in a study on two male bottlenose dolphins observed their reactions to mirrors after having a mark placed on them. Reactions such as decreased delay in approaching the mirror, repetitious head circling and close viewing of the eye or genital region that had been marked, were reported as evidence of MSR in these species.<ref>{{cite book |doi=10.1017/CBO9780511565526.026 |chapter=Evidence of self-awareness in the bottlenose dolphin (''Tursiops truncatus'') |title=Self-Awareness in Animals and Humans |year=1994 |last1=Marten |first1=Kenneth |last2=Psarakos |first2=Suchi |pages=361–379 |isbn=978-0-521-02591-1 }}</ref><ref name="Reiss">{{cite journal |last1=Reiss |first1=Diana |last2=Marino |first2=Lori |title=Mirror self-recognition in the bottlenose dolphin: A case of cognitive convergence |journal=Proceedings of the National Academy of Sciences |date=8 May 2001 |volume=98 |issue=10 |pages=5937–5942 |doi=10.1073/pnas.101086398 |pmid=11331768 |pmc=33317 |bibcode=2001PNAS...98.5937R |doi-access=free }}</ref>
* [[Killer whale]] (''Orcinus orca''): Killer whales and [[false killer whale]]s (''Pseudorca crassidens'') may be able to recognise themselves in mirrors.<ref name="Delfour">{{cite journal |last1=Delfour |first1=F |last2=Marten |first2=K |title=Mirror image processing in three marine mammal species: killer whales (''Orcinus orca''), false killer whales (''Pseudorca crassidens'') and California sea lions (''Zalophus californianus'') |journal=Behavioural Processes |date=April 2001 |volume=53 |issue=3 |pages=181–190 |doi=10.1016/s0376-6357(01)00134-6 |pmid=11334706 |s2cid=31124804 }}</ref>

===== Primates =====
* [[Bonobo]] (''[[Pan paniscus]]'')<ref name="Walraven">{{cite journal|last1=Walraven|first1=V.|last2=van Elsacker|first2=L.|last3=Verheyen|first3=R.|s2cid=38985498|year=1995|title=Reactions of a group of pygmy chimpanzees (''Pan paniscus'') to their mirror images: evidence of self-recognition|journal=Primates|volume=36|issue=1|pages=145–150|doi=10.1007/bf02381922}}</ref><ref>{{cite journal|author1=Greg C. Westergaard|author2=C. W. Hyatt|s2cid=85077838|title=The responses of bonobos (''Pan paniscus'') to their mirror images: Evidence of self-recognition|journal=Human Evolution|date=1994|volume=9|issue=4|pages=273–279|doi=10.1007/BF02435514}}</ref>
*[[Bornean orangutan]] (''[[Pongo pygmaeus]]''):<ref name="Suarez">{{cite journal |last1=Suarez |first1=Susan D. |last2=Gallup |first2=Gordon G. |title=Self-recognition in chimpanzees and orangutans, but not gorillas |journal=Journal of Human Evolution |date=February 1981 |volume=10 |issue=2 |pages=175–188 |doi=10.1016/s0047-2484(81)80016-4 |bibcode=1981JHumE..10..175S }}</ref> However, mirror tests with an infant (2-year-old), male orangutan failed to reveal self-recognition.<ref name="Robert">{{cite journal |last1=Robert |first1=S. |title=Ontogeny of mirror behavior in two species of great apes |journal=American Journal of Primatology |date=1986 |volume=10 |issue=2 |pages=109–117 |doi=10.1002/ajp.1350100202 |pmid=31979488 |s2cid=85330986 }}</ref>
* [[Chimpanzee]] (''[[Pan troglodytes]]''):<ref name="Gallup" /><ref name="miller">{{cite news |title=Minding the animals: Ethology and the obsolescence of left humanism |last=Miller |first=J. |year=2009 |magazine=American Chronicle |url=http://www.americanchronicle.com/articles/view/102661 |access-date=21 May 2009}}</ref><ref>{{cite journal |first= D. |last=Povinelli |author2=de Veer, M.|author3= Gallup Jr., G.|author4= Theall, L.|author5= van den Bos, R. |s2cid=9400080 |title=An 8-year longitudinal study of mirror self-recognition in chimpanzees (''Pan troglodytes'') |journal= Neuropsychologia |volume=41 |issue=2 |pages=229–334 |doi=10.1016/S0028-3932(02)00153-7|year=2003 |pmid=12459221 }}</ref> However, mirror tests with an infant (11 months old) male chimpanzee failed to reveal self-recognition.<ref name="Robert" /> Two young chimpanzees showed retention of MSR after one year without access to mirrors.<ref>{{cite journal |last1=Calhoun |first1=Suzanne |last2=Thompson |first2=Robert L. |title=Long-term retention of self-recognition by chimpanzees |journal=American Journal of Primatology |date=1988 |volume=15 |issue=4 |pages=361–365 |doi=10.1002/ajp.1350150409 |pmid=31968884 |s2cid=84381806 }}</ref>
* [[Western gorilla]] (''[[Gorilla gorilla]]''): Findings for western gorillas have been mixed; more so than for the other great apes. At least four studies have reported that [[gorilla]]s failed to show self-recognition.<ref name="Suarez" /><ref name="Shillito">{{cite journal|last1=Shillito|first1=D.J.|last2=Gallup|first2=G.G.|last3=Beck|first3=B.B.|year=1999|title=Factors affecting mirror behavior in western lowland gorillas, ''Gorilla gorilla''|journal=Animal Behaviour|volume=57|issue=5|pages=999–1004|doi=10.1006/anbe.1998.1062|pmid=10328785|s2cid=23093090 }}</ref><ref name="Ledbetter">{{cite journal |last1=Ledbetter |first1=David H. |last2=Basen |first2=Jeffry A. |title=Failure to demonstrate self-recognition in gorillas |journal=American Journal of Primatology |date=1982 |volume=2 |issue=3 |pages=307–310 |doi=10.1002/ajp.1350020309 |pmid=32192240 |s2cid=84369215 }}</ref><ref name="Nicholson">{{cite journal |last1=Nicholson |first1=India S. |last2=Gould |first2=Jay E. |title=Mirror mediated object discrimination and self-directed behavior in a female gorilla |journal=Primates |date=October 1995 |volume=36 |issue=4 |pages=515–521 |doi=10.1007/bf02382873 |s2cid=21450768 }}</ref> However, other studies have shown self-recognition in captive gorillas with extensive [[human]] contact. Such gorillas show less aversion to direct eye contact than wild gorillas. In wild gorillas, as in many other animals, prolonged direct eye contact is an aggressive gesture, and gorillas may fail the mirror test because they deliberately avoid closely examining or making eye contact with their reflections.<ref name="The Great Ape Project" /><ref name="Kind" /> Gorillas who have passed the MSR were habituated to the mirror before testing and were not subject to anesthesia during the marking process.<ref name="Allen">{{cite thesis | last=Allen | first=Melinda R. | date=2007 | title=Mirror self-recognition in a gorilla (''Gorilla gorilla gorilla'') | publisher=Florida International University | doi=10.25148/etd.fi13101588 | doi-access=free | degree=MS }}</ref><ref name="Posada">{{cite journal |last1=Posada |first1=Sandra |last2=Colell |first2=Montserrat |title=Another gorilla (''Gorilla gorilla gorilla'') recognizes himself in a mirror |journal=American Journal of Primatology |date=May 2007 |volume=69 |issue=5 |pages=576–583 |doi=10.1002/ajp.20355 |pmid=17154375 |s2cid=44854009 }}</ref> [[Koko (gorilla)|Koko]] was among the gorillas who passed the MSR test under these circumstances.<ref name="The Great Ape Project">{{cite book|chapter-url=http://www.animal-rights-library.com/texts-m/patterson01.htm|title=The Great Ape Project|author1=Patterson, F.|author2=Gordon, W.|publisher=St. Martin's Griffin|year=1993|editor=Cavalieri, P.|pages=58–77|chapter=The case for personhood of gorillas|editor2=Singer, P.|name-list-style=amp}}</ref><ref name="Kind">{{Cite book|url=https://books.google.com/books?id=SiuwCgAAQBAJ|title=Persons and Personal Identity |last=Kind|first=Amy |date=2015-10-02|publisher=John Wiley & Sons|isbn=9781509500246|language=en}}</ref>

===== Proboscidea =====
*[[Asian elephant]] (''Elephas maximus''): In a study performed in 2006, three female Asian elephants were exposed to a large mirror to investigate their responses. Visible marks and invisible sham-marks were applied to the elephants' heads to test whether they would pass the MSR test.<ref name="Plotnik2006" /> One of the elephants showed mark-directed behavior, though the other two did not. An earlier study failed to find MSR in two Asian elephants;<ref name="Povinelli1989">{{cite journal |last1=Povinelli |first1=Daniel J. |title=Failure to find self-recognition in Asian elephants (''Elephas maximus'') in contrast to their use of mirror cues to discover hidden food. |journal=Journal of Comparative Psychology |date=1989 |volume=103 |issue=2 |pages=122–131 |doi=10.1037/0735-7036.103.2.122 }}</ref> it was claimed this was because the mirror was too small.<ref name="Plotnik2006">{{cite journal|last1=Plotnik|first1=J.M.|last2=de Waal|first2=F.B.M.|last3=Reiss|first3=D.|year=2006|title=Self-recognition in an Asian elephant|journal=Proceedings of the National Academy of Sciences|volume=103|issue=45|pages=17053–17057|doi=10.1073/pnas.0608062103|pmid=17075063|bibcode=2006PNAS..10317053P|pmc=1636577|doi-access=free}}</ref><ref name="Elephantselfawareness">{{cite news | title = Elephants' Jumbo Mirror Ability | publisher = [[BBC News]] | url = http://news.bbc.co.uk/2/hi/science/nature/6100430.stm | access-date = 2007-10-31 | date=2006-10-31}}</ref>

===== Rodents =====

* [[House mouse]] (''Mus musculus)''<ref>{{Cite web |date=2023-12-06 |title=Mouse passes mirror test, joining elite club of 'self-aware' animals |url=https://newatlas.com/biology/mouse-passes-mirror-test/ |access-date=2025-02-20 |website=New Atlas |language=en-US}}</ref>

==== Birds ====
[[File:Mirror-Induced-Behavior-in-the-Magpie-(Pica-pica)-Evidence-of-Self-Recognition-pbio.0060202.sv008.ogv|thumb|220px|Video of the responses of a European magpie in an MSR test: The magpie repeatedly attempts to remove the marks.]]
* [[Eurasian magpie]] (''Pica pica''): The Eurasian magpie is the first non-mammal to have been found to pass the mirror test. In 2008, researchers applied a small red, yellow, or black sticker to the throat of five Eurasian magpies, where they could be seen by the bird only by using a mirror. The birds were then given a mirror. The feel of the sticker on their throats did not seem to alarm the magpies. However, when the birds with colored stickers glimpsed themselves in the mirror, they scratched at their throats—a clear indication that they recognised the image in the mirror as their own. Those that received a black sticker, invisible against the black neck feathers, did not react.<ref name="Prior">{{cite journal
 |last1=Prior|first1=H.
 |last2=Schwarz|first2=A.
 |last3=Güntürkün|first3=O. 
 |title=Mirror-induced behavior in the magpie (''Pica pica''): Evidence of self-recognition 
 |journal=PLOS Biology 
 |year=2008 
 |doi=10.1371/journal.pbio.0060202 
 |doi-access=free
 |volume=6 
 |page=e202 
 |pmid=18715117 
 |issue=8 
 |pmc=2517622 
}}</ref> In 2020, researchers attempted to closely replicate the 2008 study with a larger number of magpies, and failed to confirm the results of the 2008 study. The researchers stated that while these results did not disprove the 2008 study, the failure to replicate indicated the results of the original study should be treated with caution.<ref name="Solar">{{cite journal
 |last1=Solar|first1=M.
 |last2=Colmenero|first2=J.
 |last3=Pérez-Contreras|first3=T. 
 |last4=Peralta-Sánchez|first4=J.
 |title=Replication of the mirror mark test experiment in the magpie (''Pica pica'') does not provide evidence of self-recognition
 |journal=J Comp Psychol
 |year=2020
 |volume=134
 |issue=4
 |pages=363–371
 |doi=10.1037/com0000223
 |pmid=32406720
|s2cid=218636079
 }}</ref>

* [[Indian house crow]] (''Corvus splendens''): House crows were found to pass the mirror test in 2019. Six wild-caught crows had a red or yellow mark applied to their throat, then given a mirror. Their reactions were then compared to behaviour exhibited when the mark was applied in absence of a mirror, and when a black mark — not visible against the black throat — was applied both with and without a mirror. Four of the six birds displayed mark-directed behaviour spontaneously when first shown a mirror. The behaviours of these birds were then compared; the birds showed statistically increased levels of plumage ruffling and head shaking in the mark-mirror trials.<ref>{{cite journal |last1=Buniyaadi |first1=Amaan |last2=Tahajjul Taufique |first2=S. K. |last3=Kumar |first3=Vinod |title=Self-recognition in corvids: evidence from the mirror-mark test in Indian house crows (Corvus splendens) |journal=Journal of Ornithology |date=2019-11-05 |volume=161 |issue=2 |pages=341–350 |doi=10.1007/s10336-019-01730-2}}</ref> Another study done on five house crows failed to replicate the result, to which they list several experimental differences, such as length of mirror and mark exposure and sticker weight. They additionally note that only two of the four crows that exhibited mark-directed behaviour in the original experiment did so at a high frequency, and that of the other two, one was preening at high levels during mirror exposure without a mark— suggesting that any perceived mark-directed behaviours observed could be a part of general preening behaviour. These authors conclude that under their [[paradigm]], house crows do not appear to pass the mark test, but also emphasize the high level of variability in results from the mark test and the necessity for testing to be done with larger sample sizes.<ref>{{cite journal |last1=Parishar |first1=Pooja |last2=Mohapatra |first2=Alok Nath |last3=Iyengar |first3=Soumya |title=Investigating Behavioral Responses to Mirrors and the Mark Test in Adult Male Zebra Finches and House Crows |journal=Frontiers in Psychology |date=2021-04-12 |volume=12 |doi=10.3389/fpsyg.2021.637850 |doi-access=free |pmid=33935888 |pmc=8082158 }}</ref>

* Some [[pigeons]] can pass the mirror test after training in the prerequisite behaviors.<ref name="uchbino">{{Cite journal |last1=Uchino |first1=Emiko |last2=Watanabe |first2=Shigeru |date=2014-11-01 |title=Self-recognition in pigeons revisited |journal=Journal of the Experimental Analysis of Behavior |language=en |volume=102 |issue=3 |pages=327–334 |doi=10.1002/jeab.112 |pmid=25307108 |s2cid=31499014 }}</ref> In 1981, American psychologist [[B. F. Skinner]] found that pigeons are capable of passing a highly modified mirror test after extensive training.<ref>{{Cite journal |last1=Epstei |first1=Robert |last2=Lanza |first2=Robert P. |last3=Skinner |first3=B. F. |date=1981-05-08 |title="Self-Awareness" in the Pigeon |url=https://www.science.org/doi/10.1126/science.212.4495.695 |journal=Science |language=en |volume=212 |issue=4495 |pages=695–696 |doi=10.1126/science.212.4495.695 |issn=0036-8075 |pmid=17739404|bibcode=1981Sci...212..695E |url-access=subscription }}</ref><ref>[https://web.archive.org/web/20110719225835/http://psychology.lafayette.edu/files/2010/06/selfaware.mov This is video of one such test]</ref> In the experiment, a pigeon was [[Operant conditioning|trained]] to look in a mirror to find a response key behind it, which the pigeon then turned to peck to obtain food. Thus, 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. However, [[Animal training|untrained]] pigeons have never passed the mirror test.<ref name="de Waal2008">{{cite journal |last1=de Waal |first1=Frans B. M |title=The Thief in the Mirror |journal=PLOS Biology |date=19 August 2008 |volume=6 |issue=8 |pages=e201 |doi=10.1371/journal.pbio.0060201 |pmid=18715116 |pmc=2517621 |doi-access=free }}</ref>

==== Fish ====
* [[Bluestreak cleaner wrasse]] (''Labroides dimidiatus''): According to a study done in 2019, [[cleaner wrasses]] were the first fish observed to pass the mirror test.<ref>{{Cite web |last1=Yirka |first1=Bob |last2=Phys.org |title=Bluestreak cleaner wrasse found to recognize self in photograph after passing mirror test |url=https://phys.org/news/2023-02-bluestreak-cleaner-wrasse-mirror.html |access-date=2023-02-07 |website=phys.org |language=en}}</ref><ref>{{Cite web |last1=Yirka |first1=Bob |last2=Phys.org |title=Small fish passes classic self-awareness test |url=https://phys.org/news/2018-09-small-fish-classic-self-awareness.html |access-date=2023-02-07 |website=phys.org |language=en}}</ref> The bluestreak cleaner wrasse is a tiny tropical reef [[cleaner fish]]. Cleaner fish have an adapted evolutionary behavior in which they remove parasites and dead tissue from larger fish. When put through the mirror test, using a benign brown gel injected into the skin of the fish, and resembling a parasite, the cleaner wrasse showed all the behaviors of passing through the phases of the test. When provided with a colored tag in a modified mark test, the fish attempted to scrape off this tag by scraping their bodies on the side of the mirror. Gordon Gallup believes the cleaner wrasses' behavior can be attributed to something other than recognizing itself in a mirror. Gallup has argued that a cleaner wrasse's job in life is to be aware of ectoparasites on the bodies of other fish, so it would be hyper aware of the fake parasite that it noticed in the mirror, perhaps seeing it as a parasite that it needed to clean off of a different fish. The authors of the study retort that because the fish checked itself in the mirror before and after the scraping, this means that the fish has self-awareness and recognizes that its reflection belongs to its own body.<ref>{{cite web |last=Buehler |first=Jake |url=https://www.nationalgeographic.com/animals/article/fish-cleaner-wrasse-self-aware-mirror-test-intelligence-news |title=This tiny fish can recognize itself in a mirror. Is it self-aware? |date=2019-02-08 |website=[[National Geographic]] |access-date=2025-03-28 |archive-url=https://web.archive.org/web/20210302171854/https://www.nationalgeographic.com/animals/article/fish-cleaner-wrasse-self-aware-mirror-test-intelligence-news |archive-date=2021-03-02 |url-status=live}}</ref><ref>{{Cite web|title=A species of fish has passed the mirror test for the first time|url=https://www.newscientist.com/article/2178329-a-species-of-fish-has-passed-the-mirror-test-for-the-first-time/|last=Ye|first=Yvaine|website=New Scientist|language=en-US|access-date=2020-05-11}}</ref><ref name="rxiv-fish">{{cite journal |doi=10.1371/journal.pbio.3000021 |doi-access=free|title=If a fish can pass the mark test, what are the implications for consciousness and self-awareness testing in animals? |year=2019 |last1=Kohda|first1=Masanori |last2=Hotta|first2=Takashi |last3=Takeyama|first3=Tomohiro |last4=Awata|first4=Satoshi |last5=Tanaka|first5=Hirokazu |last6=Asai|first6=Jun-ya |last7=Jordan|first7=Alex L. |journal=PLOS Biology |volume=17|issue=2|pages=e3000021|pmid=30730878|pmc=6366756}}</ref> The cleaner wrasses, when tested, spent a large amount of time with the mirror when they were first getting acquainted with it, without any training. Importantly, the cleaner wrasses performed scraping behavior with the colored mark, and they did not perform the same scraping behavior without the colored mark in the presence of the mirror, nor when they were with the mirror and had a transparent mark.<ref>{{Cite journal |doi = 10.1371/journal.pbio.3000112 |pmid = 30730875|title = Fish, mirrors, and a gradualist perspective on self-awareness|journal = PLOS Biology|volume = 17|issue = 2|pages = e3000112|year = 2019|last1 = De Waal|first1 = Frans B. M.|pmc = 6366752 | doi-access=free }}</ref> Following various objections, the researchers published a follow-up study in 2022, where they did the mirror test on a larger sample of wrasses and experimented with several marking techniques. The new results "increase[d] [the researchers'] confidence that cleaner fish indeed pass the mark test", although wrasses attempted to scrape off the mark only when it resembled a parasite.<ref>{{Cite web|last=Ferreira|first=Becky|title=Fish Might Really Be Self-Aware, New Study Finds|url=https://www.vice.com/en/article/fish-might-really-be-self-aware-new-study-finds/|archive-url=https://web.archive.org/web/20220218072538/https://www.vice.com/en/article/z3nwgw/fish-might-really-be-self-aware-new-study-finds|archive-date=February 18, 2022|access-date=February 19, 2022|website=Vice|url-status=live|date=17 February 2022 }}</ref><ref>{{Cite journal|last1=Kohda|first1=Masanori|last2=Sogawa|first2=Shumpei|last3=Jordan|first3=Alex L.|last4=Kubo|first4=Naoki|last5=Awata|first5=Satoshi|last6=Satoh|first6=Shun|last7=Kobayashi|first7=Taiga|last8=Fujita|first8=Akane|last9=Bshary|first9=Redouan|date=2022-02-17|title=Further evidence for the capacity of mirror self-recognition in cleaner fish and the significance of ecologically relevant marks|journal=PLOS Biology|language=en|volume=20|issue=2|pages=e3001529|doi=10.1371/journal.pbio.3001529|pmid=35176032 |issn=1545-7885|pmc=8853551 |doi-access=free }}</ref> Another study in 2024 found that cleaner wrasse that initially showed aggression to photographs 10% larger and 10% smaller than themselves ceased confrontation with 10% larger photographs upon encountering their reflection.<ref>{{Cite journal |last1=Kobayashi |first1=Taiga |last2=Kohda |first2=Masanori |last3=Awata |first3=Satoshi |last4=Bshary |first4=Redouan |last5=Sogawa |first5=Shumpei |date=2024-09-11 |title=Cleaner fish with mirror self-recognition capacity precisely realize their body size based on their mental image |journal=Scientific Reports |language=en |volume=14 |issue=1 |pages=20202 |doi=10.1038/s41598-024-70138-7 |pmid=39261520 |issn=2045-2322|pmc=11390716 |bibcode=2024NatSR..1420202K }}</ref>
*[[Giant oceanic manta ray]] (''Mobula birostris''): In 2016 a modified mirror test done on two captive manta rays showed that they exhibited behavior associated with [[self-awareness]] (i.e. contingency checking and unusual self-directed behavior).<ref name="Ari" />

====Crustaceans====
*[[Atlantic ghost crab]] (''Ocypode quadrata''): A 2023 study found that these crabs seem to be capable of recognizing themselves in a mirror. The study's author concluded that the data indicate that the crabs have "a rudimentary form of self-awareness".<ref name="Robinson2023">{{cite journal |last1=Robinson |first1=T. |title=Mirror self-recognition in ghost crab (Ocypode quadrata) |journal=Animal Cognition |date=14 June 2023 |volume=26 |issue=5 |pages=1539–1549 |doi=10.1007/s10071-023-01800-2 |pmid=37314594 |url=https://link.springer.com/article/10.1007/s10071-023-01800-2 |access-date=25 November 2023|url-access=subscription }}</ref>
'''Cephalopods'''
*[[Mimic octopus]] (''Thaumoctopus mimicus''): A video in 2025 showed a Mimic Octopus recognising itself in a mirror.<ref>{{Cite AV media |url=https://www.youtube.com/watch?v=FQYSJ6igK_w |title=Sea Creatures vs Mirror: Do They Recognize Themselves (or Attack)? |date=2025-02-12 |last=Barny Dillarstone |access-date=2025-02-20 |via=YouTube}}</ref>

==== Insects ====
* [[Myrmica rubra]], [[Myrmica ruginodis]], and [[Myrmica sabuleti]]: A 2015 study found that individuals ants of these three ant species would attempt to clean themselves after being exposed to a mirror and seeing a blue dot on their bodies.<ref>{{cite journal |last1=Lei |first1=Yanyu |title=Sociality and self-awareness in animals |journal=Frontiers in Psychology |date=9 January 2023 |volume=13 |doi=10.3389/fpsyg.2022.1065638 |doi-access=free |pmid=36710826 |pmc=9881685 }}</ref>{{better source needed|Sussy journal; cf. our own article [[Frontiers in Psychology]]|date=May 2025}}

=== Animals that have failed ===
Some animals that have reportedly failed the classic MSR test include:

==== Mammals ====

===== Carnivorans =====
* [[Sea lion]]s (''Zalophus californianus'')<ref name="Delfour" /><ref name="Hill">{{cite journal|last1=Hill|first1=H.M.|last2=Webber|first2=K.|last3=Kemery|first3=A.|last4=Garcia|first4=M.|last5=Kuczaj|first5=S.A.|year=2015|title=Can sea lions' (''Zalophus californianus'') use mirrors to locate an object?|journal=International Journal of Comparative Psychology|volume=28|doi=10.46867/ijcp.2015.28.00.08|url=http://escholarship.org/uc/item/8wx583w7|doi-access=free}}</ref>
* [[Giant panda]] (''Ailuropoda melanoleuca''): In one study, 34 captive giant pandas of a wide range of ages were tested. None of the pandas responded to the mark and many reacted aggressively towards the mirror, causing the researchers to consider the pandas viewed their reflection as a [[conspecific]].<ref name="Panda">{{cite journal|last1=Ma|first1=X.|last2=Jin|first2=Y.|last3=Luo|first3=B.|last4=Zhang|first4=G.|last5=Wei|first5=R.|last6=Liu|first6=D.|year=2015|title=Giant pandas failed to show mirror self-recognition|journal=Animal Cognition|volume=18|issue=3|pages=713–721|doi=10.1007/s10071-015-0838-4|pmid=25609263|s2cid=17801599}}</ref>
*[[Dog]]s (''Canis lupus familiaris''): Dogs either treat the image as another animal, or come to ignore it completely.<ref>{{Cite web|title=Does my Dog Recognize Himself in a mirror?|url= https://www.psychologytoday.com/us/blog/canine-corner/201107/does-my-dog-recognize-himself-in-mirror |access-date=2022-01-15|website=Psychology Today|language=en}}</ref>

===== Primates =====
* [[Stump-tailed macaque]] (''Macaca arctoides'')<ref name="Gallup" /><ref name="Panda" />
* [[Crab-eating macaque]] (''Macaca fascicularis'')<ref name="Panda" />
* [[Black-and-white colobus]] (''Colobus guereza'')<ref name="Shaffer">{{cite journal |last1=Shaffer |first1=Victoria A. |last2=Renner |first2=Michael J. |title=Black-and-White Colobus Monkeys (''Colobus guereza'') do not Show Mirror Self-Recognition |journal=International Journal of Comparative Psychology |date=31 December 2000 |volume=13 |issue=3 |doi=10.46867/C4H01J |s2cid=54843214 |url=https://escholarship.org/uc/item/3xh2d90n |doi-access=free }}</ref>
* [[Hamadryas baboon]] (''Papio hamadryas'')<ref name="Panda" />
* [[Cotton-top tamarin]] (''Saguinus oedipus'')<ref name="Tamarin">{{cite journal | first1= M.|last1=Hauser | first2=C.|last2=Miller | first3=K.|last3=Liu | first4=R.|last4=Gupta | year=2001 | journal=American Journal of Primatology | volume=137 | issue=December 2000|title=Cotton-top tamarins (''Saguinus oedipus'') fail to show mirror-guided self-exploration |pages=131–137|doi=10.1002/1098-2345(200103)53:3<131::AID-AJP4>3.0.CO;2-X | pmid=11253848 |s2cid=17250348 }}</ref>
* [[Chacma Baboon]] (Papio Ursius)<ref>{{Cite web |last=Dasgupta |first=Shreya |date=2025-02-12 |title=Wild baboons don't recognize their own mirror reflections |url=https://news.mongabay.com/short-article/wild-baboons-dont-recognize-their-own-mirror-reflections/ |access-date=2025-02-20 |website=Mongabay Environmental News |language=en-US}}</ref>

==== Birds ====
* [[Grey parrot]]<ref>{{cite journal|last1=Lin |first1=Yi |last2=Pey |first2=Enle |last3=Liu |first3=Qunxiu |last4=Ma |first4=Jun |last5=Zhang |first5=Endi |last6=Zhao |first6=Junyi |last7=Chen |first7=Min |url=https://www.tandfonline.com/doi/full/10.1080/03949370.2023.2178031 |title=Mirror responses in African grey parrot (Psittacus erithacus) support the gradualist perspective on mirror self-recognition |journal=Ethology Ecology & Evolution |doi=10.1080/03949370.2023.2178031 |date=27 February 2023 |volume=35 |issue=6 |pages=730–745 |bibcode=2023EtEcE..35..730L |archive-url=https://web.archive.org/web/20250311152121/https://www.tandfonline.com/doi/citedby/10.1080/03949370.2023.2178031 |archive-date=2025-03-11}}</ref>
* [[New Caledonian crow]]<ref>{{cite news|last=Davies |first=E. |url=https://www.bbc.co.uk/nature/14897544 |title=Crows use mirrors to find food |publisher=[[BBC]] Nature |date=20 September 2011 |access-date=19 May 2012 |archive-url=https://web.archive.org/web/20110921020334/https://www.bbc.co.uk/nature/14897544 |archive-date=2011-09-21}}</ref>
* [[Jackdaw]]<ref name="Soler">{{cite journal|last1=Soler|first1=M.|last2=Pérez-Contreras|first2=T.|last3=Peralta-Sánchez|first3=J.M. |year=2014 |title=Mirror-mark tests performed on jackdaws reveal potential methodological problems in the use of stickers in avian mark-test studies |journal=PLOS ONE |volume=9|issue=1 |pages=e86193 |doi=10.1371/journal.pone.0086193 |pmid=24475085 |pmc=3903501 |bibcode=2014PLoSO...986193S |doi-access=free}}</ref>
* [[Great tit]] (''Parus major'')<ref name="Kraft">{{cite journal | last1=Kraft|first1=F.L. | last2=Forštová|first2=T. |last3=Utku Urhan|first3=A. | last4=Exnerová|first4=A. | last5=Brodin|first5=A. | year=2017 | title=No evidence for self-recognition in a small passerine, the great tit (''Parus major'') judged from the mark/mirror test | journal=Animal Cognition | volume=20 | issue=6 | pages = 1049–1057 | doi = 10.1007/s10071-017-1121-7 | doi-access=free | pmid=28762195 | pmc= 5640729 }}</ref>

==== Fish ====
*The Tanganyikan cichlid, or daffodil cichlid (''[[Neolamprologus pulcher]]''), is another fish that has failed the mirror test, according to a study done in 2017. Although not [[cleaner fish]] like the [[cleaner wrasses]], these fish are typically regarded as socially intelligent and can recognize conspecifics in their social groups. Therefore, they would theoretically make good candidates for the mirror test, but they ended up failing. Similar to the cleaner wrasse, the Tanganyikan cichlid first exhibited signs of aggression towards the mirrored image. After a colored mark was injected, the researchers found no increased scraping or trying to remove the mark, and the cichlids did not observe the side with the mark any longer than it would have otherwise. This demonstrates a lack of contingency checking and means that the Tanganyikan cichlid did not pass the mirror test.<ref name="Hotta">{{cite journal |vauthors=Hotta T, Komiyama S, Kohda M | year=2018 | journal = Animal Cognition | volume= 21 | issue = 1 | pages = 127–136 | title = A social cichlid fish failed to pass the mark test | doi = 10.1007/s10071-017-1146-y | pmid = 29150813| s2cid=3950089 }}</ref>

==== Cephalopods ====
* [[Octopodes]] oriented towards their image in a mirror, but no difference in their behaviour (as observed by humans) was seen in this condition when compared with a view of other octopodes.<ref>{{cite journal |last1=Mather |first1=Jennifer A. |last2=Kuba |first2=Michael J. |title=The cephalopod specialties: complex nervous system, learning, and cognition |journal=Canadian Journal of Zoology |date=June 2013 |volume=91 |issue=6 |pages=431–449 |doi=10.1139/cjz-2013-0009 |bibcode=2013CaJZ...91..431M }}</ref>

=== Animals that may pass ===

==== Mammals ====

===== Primates =====
[[Gibbon]] (g. ''Hylobates'', ''Symphalangus'' and ''Nomascus'') have failed to show self-recognition in at least two tests.<ref name="Suddendorf">{{cite journal |last1=Suddendorf |first1=Thomas |last2=Collier-Baker |first2=Emma |title=The evolution of primate visual self-recognition: evidence of absence in lesser apes |journal=Proceedings of the Royal Society B: Biological Sciences |date=7 May 2009 |volume=276 |issue=1662 |pages=1671–1677 |doi=10.1098/rspb.2008.1754 |pmid=19324830 |pmc=2660989 }}</ref><ref name="Hyatt1998">{{cite journal| author=Hyatt, C.W. |year=1998 |title=Responses of gibbons (''Hylobates lar'') to their mirror images |journal=American Journal of Primatology |volume=45 |issue=3 |pages=307–311 |doi=10.1002/(SICI)1098-2345(1998)45:3<307::AID-AJP7>3.0.CO;2-# |pmid=9651653|s2cid=196596255 }}</ref> However, modified mirror tests with three species of [[gibbon]]s (''Hylobates syndactylus'', ''H. gabriellae'', ''H. leucogenys'') in 2000 showed convincing evidence of self-recognition even though the animals failed the standard version of the mirror test.<ref>{{cite journal |last1=Ujhelyi |first1=M. |last2=Merker |first2=B. |last3=Buk |first3=P. |last4=Geissmann|first4=T.|year=2000|title=Observations on the behavior of gibbons (''Hylobates leucogenys'', ''H. gabriellae'', and ''H. lar'') in the presence of mirrors |journal=Journal of Comparative Psychology |volume=114 |issue=3 |pages=253–262 |doi=10.1037/0735-7036.114.3.253 |pmid=10994841 |s2cid=7350911}}</ref> Another study published in 2009 documents 12 cases of spontaneous self-recognition in front of the mirror by a pair of [[siamang]]s (Symphalangus syndactylus).<ref>{{cite journal |last1=Heschl |first1=Adolf |last2=Fuchsbichler |first2=Conny |title=Siamangs (Hylobates syndactylus) Recognize their Mirror Image |journal=International Journal of Comparative Psychology |date=2009 |volume=22 |issue=4 |pages=221–233|doi=10.46867/IJCP.2009.22.04.03 |doi-access=free }}</ref> [[Capuchin monkey]] (''Cebus apella'') did not pass in one test<ref>{{cite journal |last1=Roma |first1=P. |last2=Silberberg |first2=A. |last3=Huntsberry |first3=M. |last4=Christensen |first4=C. |last5=Ruggiero |first5=A |last6=Suomi |first6=S. |year=2007 |title=Mark tests for mirror self-recognition in Capuchin monkeys (''Cebus apella'') trained to touch marks |journal=American Journal of Primatology |volume=69 |issue=9 |pages=989–1000 |doi=10.1002/ajp.20404 |pmid=17253635 |s2cid=41302656}}</ref> but recognized the reflection as special in another.<ref>{{Cite journal |last=de Waal |first=Frans D. B. |date=July 29, 2005 |title=The monkey in the mirror: Hardly a stranger |journal=Proceedings from the National Academy of Sciences |volume=102 |issue=32 |pages=11140–11147 |doi=10.1073/pnas.0503935102 |doi-access=free |pmid=16055557 |pmc=1183568 |bibcode=2005PNAS..10211140D }}</ref>

[[Rhesus macaque]] (''Macaca mulatta'') Though macaques failed the original mark test,<ref name="Gallup" /> they have been reported to exhibit other behaviours that indicate self-recognition.<ref name="Lauwereyns">{{cite journal |last1=Rajala |first1=A.Z. |last2=Reininger |first2=K.R. |last3=Lancaster |first3=K.M. |last4=Populin |first4=L.C. |year=2010 |title=Rhesus monkeys (''Macaca mulatta'') do recognize themselves in the mirror: Implications for the evolution of self-recognition |journal=PLOS ONE |volume=5 |issue=9 |pages=e12865 |bibcode=2010PLoSO...512865R |doi=10.1371/journal.pone.0012865 |pmc=2947497 |pmid=20927365 |doi-access=free}}</ref> Rhesus macaques have been observed to use mirrors to study otherwise-hidden parts of their bodies, such as their genitals and implants in their heads.<ref>{{Cite web |last=Pebsworth |first=Paula |date=October 24, 2023 |title=International Primatology Lecture 23 - Dr. Paula Pebsworth |url=https://www.youtube.com/watch?v=j_hMb-aNd4Q&t=2590s |access-date=November 20, 2024 |website=YouTube: Kyoto University's Center for International Collaboration and Advanced Studies in Primatology}}</ref> It has been suggested this demonstrates at least a partial self-awareness, although further study is needed.<ref name="Wired">{{cite news |author=Brandon, K. |date=29 September 2010 |title=Monkeys see selves in mirror, open a barrel of questions |url=https://www.wired.com/wiredscience/2010/09/monkey-self-awareness/ |archive-url=https://web.archive.org/web/20110114144225/https://www.wired.com/wiredscience/2010/09/monkey-self-awareness/ |archive-date=January 14, 2011 |access-date=1 October 2010 |magazine=Wired}}</ref>

===== Pigs =====
[[Pig]]s can use visual information seen in a mirror to find food. In a 2009 experiment, seven of the eight pigs who spent 5 hours with a mirror were able to find a bowl of food hidden behind a wall and revealed using a mirror. Pigs that had no experience with mirrors, looked behind the mirror for the food.<ref>{{Cite journal|last1=Broom|first1=D. M. |last2=Sena|first2=H. |last3=Moynihan|first3=K. L. |year=2009|title=Pigs learn what a mirror image represents and use it to obtain information|journal=Animal Behaviour|volume=78|issue=5|pages=1037–1041|doi=10.1016/j.anbehav.2009.07.027|s2cid=53175225}}</ref> [[BBC Earth]] also showed the food bowl test,<ref>{{Cite web|title=Smart Pigs vs Kids &#124; Extraordinary Animals |last= BBC Earth|url=https://www.youtube.com/watch?v=mza1EQ6aLdg|via=YouTube |date=Feb 19, 2014}}</ref> and the "matching shapes to holes" test, in the ''Extraordinary Animals'' series.<ref>{{Cite web|title=Are Pigs Self-Aware?&#124; The Private Life of Pigs &#124; Real Wild|url=https://www.youtube.com/watch?v=mqD3FkDgGYk|via=YouTube}}</ref>

There is evidence of self-recognition when presented with their reflections. So far, pigs have not been observed to pass the mirror mark test, however.<ref>{{cite web | url=https://mypigfilledlife.org/adopt/f/did-you-know-pigs-are-self-aware | title=Did you know? Pigs are self aware! }}</ref>

==== Birds ====
[[Adelie penguins]] do not react as if they would react to a wild bird, and when presented with a mirror, gestured as if they recognized themselves. However, they were not bothered enough by marks on their face to notice. <ref>{{cite web | url=https://phys.org/news/2022-12-mirror-wild-penguins-self-awareness.html | title=Mirror test of wild penguins suggests they may possess self-awareness }}</ref>

==== Fish ====
Two captive [[giant manta rays]] showed frequent, unusual and repetitive movements in front of a mirror, suggesting contingency checking. They also showed unusual self-directed behaviors when exposed to the mirror.<ref name="Ari">{{cite journal |last1=Ari |first1=C. |last2=D'Agostino|first2=D.P. |year=2016 |title=Contingency checking and self-directed behaviors in giant manta rays: Do elasmobranchs have self-awareness?|journal=Journal of Ethology|volume=34|issue=2|pages=167–174|doi=10.1007/s10164-016-0462-z|s2cid=18628472}}</ref> Manta rays have the largest brains of all fish. In 2016, Csilla Ari tested captive manta rays at the Atlantis Aquarium in the Bahamas by exposing them to a mirror. The manta rays appeared to be extremely interested in the mirror. They behaved strangely in front the mirror, including doing flips and moving their fins. They also blew bubbles. They did not interact with the reflection as if it were another manta ray; they did not try to socialize with it. However, only an actual mirror test can determine if they actually recognize their own reflections, or if they are just demonstrating exploratory behavior. A classic mirror test has yet to be done on manta rays.<ref name=":0">{{cite journal|author=Amanda Pachniewska|date=April 15, 2015|title=List of Animals That Have Passed the Mirror Test|url=http://www.animalcognition.org/2015/04/15/list-of-animals-that-have-passed-the-mirror-test/|website=Animal Cognition}}</ref>

Another fish that may pass the mirror test is the common archerfish, ''[[Toxotes chatareus]]''. A study in 2016 showed that archerfish can discriminate between human faces. Researchers showed this by testing the archerfish, which spit a stream of water at an image of a face when they recognized it. The archerfish would be trained to expect food when it spat at a certain image. When the archerfish was shown images of other human faces, the fish did not spit. They only spit for the image that they recognized.<ref>{{Cite journal |doi = 10.1038/srep27523|pmid = 27272551|title = Discrimination of human faces by archerfish (''Toxotes chatareus'')|journal = Scientific Reports|volume = 6|pages = 27523|year = 2016|last1 = Newport|first1 = Cait|last2 = Wallis|first2 = Guy|last3 = Reshitnyk|first3 = Yarema|last4 = Siebeck|first4 = Ulrike E.|bibcode = 2016NatSR...627523N|pmc = 4895153}}</ref> Archerfish normally, in the wild, use their spitting streams to knock down prey from above into the water below. The study showed that archerfish could be trained to recognize a three-dimensional image of one face compared to an image of a different face and would spit at the face when they recognized it. The archerfish were even able to continue recognizing the image of the face even when it was rotated 30, 60 and 90°.<ref>{{cite magazine|url=https://www.nationalgeographic.com/animals/2018/10/archerfish-animal-cognition-intelligence-human-faces-news/|archive-url=https://web.archive.org/web/20181101184156/https://www.nationalgeographic.com/animals/2018/10/archerfish-animal-cognition-intelligence-human-faces-news/|url-status=dead|archive-date=1 November 2018|title=Water-spitting fish can identify and remember human faces|first=Jason|last=Bittel|date=18 October 2018|magazine=[[National Geographic]]}}</ref>

==Humans==
[[File:Mirror baby.jpg|thumb|225px|A human child exploring their reflection]]
The rouge test is a version of the mirror test used with human children.<ref name=Amsterdam>{{cite journal |doi=10.1002/dev.420050403 |author=Beulah Amsterdam |title=Mirror self-image reactions before age two |journal=Developmental Psychobiology |volume=5 |issue=4 |pages=297–305 |year=1972 |pmid=4679817}}</ref> Using [[rouge (cosmetics)|rouge]] makeup, an experimenter surreptitiously places a dot on the face of the child. The children are then placed in front of a mirror and their reactions are monitored; depending on the child's development, distinct categories of responses are demonstrated. This test is widely cited as the primary measure for mirror self-recognition in human children.<ref name=Lewis>{{cite book |title=Social cognition and the acquisition of self |url=https://archive.org/details/socialcognitiona0000lewi |url-access=registration |last=Lewis |first=M. |author2=Brooks-Gunn, J. |year=1979 |publisher=Plenum Press |location=New York |isbn=978-0-306-40232-6 |page= [https://archive.org/details/socialcognitiona0000lewi/page/296 296]}}</ref><ref name=Priel>{{cite journal |doi=10.1016/0022-0965(86)90038-X |author=Priel, Beatrice |author2=de Schonen, Scania |title=Self-Recognition: A Study of a Population without Mirrors |journal=Journal of Experimental Child Psychology |volume=41 |issue=2 |pages=237–250 |year=1986 |pmid=3701250}}</ref><ref name=Sedikides>Sedikides, C. & Spencer, S.J. (Eds.) (2007). ''The Self''. New York: Psychology Press</ref>

There is criticism that passing a rouge test may be culturally motivated, and that what is commonly thought about mirror self-recognition actually applies only to children of Western countries. A study from 2010 tested children from rural communities in Kenya, Fiji, Saint Lucia, Grenada and Peru, as well as urban United States and rural Canada. The majority of children from the US and Canada passed the MSR test, but fewer children from the other regions passed the MSR test. In the Kenya test, only 3% of children aged 18–72 months touched the mark. In the Fiji test, none of the children aged 36–55 months touched the mark. The other non-Western rural children scored much better, but still markedly worse than their Western counterparts.<ref>{{cite journal | url=https://journals.sagepub.com/doi/abs/10.1177/0022022110381114?journalCode=jcca | doi=10.1177/0022022110381114 | title=Cultural Variations in Children's Mirror Self-Recognition | date=2011 | last1=Broesch | first1=Tanya | last2=Callaghan | first2=Tara | last3=Henrich | first3=Joseph | last4=Murphy | first4=Christine | last5=Rochat | first5=Philippe | journal=Journal of Cross-Cultural Psychology | volume=42 | issue=6 | pages=1018–1029 | s2cid=18326326 | url-access=subscription }}</ref>

===Developmental reactions===
In a study in 1972, from the ages of 6 to 12 months, children typically saw a "sociable playmate" in the mirror's reflection. Self-admiring and embarrassment usually began at 12 months, and at 14 to 20 months, most children demonstrated avoidance behaviors. By 20 to 24 months, self-recognition climbed to 65%. Children did so by evincing mark-directed behavior; they touched their own noses or tried to wipe the marks off.<ref name="Amsterdam" /> In another study, in 1974, at 18 months, half of children recognized the reflection in the mirror as their own.<ref name="Lewis" />

Self-recognition in mirrors apparently is independent of familiarity with reflecting surfaces.<ref name=Priel/> In some cases, the rouge test has been shown to have differing results, depending on sociocultural orientation. For example, a [[Nso people|Cameroonian Nso]] sample of infants 18 to 20 months of age had an extremely low amount of self-recognition outcomes at 3.2%. The study also found two strong predictors of self-recognition: object stimulation (maternal effort of attracting the attention of the infant to an object either person touched) and mutual eye contact.<ref name=Keller>{{cite journal |author=Heidi Keller |author2=Relindis Yovsi |author3=Joern Borke |author4=Joscha Kärtner |author5=Henning Jensen |author6=Zaira Papaligoura  |title=Developmental Consequences of Early Parenting Experiences: Self-Recognition and Self-Regulation in Three Cultural Communities |journal=Child Development |volume=75 |issue=6 |pages=1745–1760 |year=2004|doi=10.1111/j.1467-8624.2004.00814.x |pmid=15566377 |s2cid=601275 }}</ref> A strong correlation between self-concept and [[object permanence]] have also been demonstrated using the rouge test.<ref name=Bertenthal>{{cite journal |first1=Bennett I.|last1=Bertenthal |first2=Kurt W.|last2=Fischer |title=Development of Self-Recognition in the Infant |journal=Developmental Psychology |volume=14 |pages=44–50 |year= 1978 | doi = 10.1037/0012-1649.14.1.44 |citeseerx=10.1.1.550.1903 }}</ref>

===Implications===
The rouge test is a measure of [[self-concept]]; the child who touches the rouge on their own nose upon looking into a mirror demonstrates the basic ability to understand self-awareness.<ref>{{cite journal|doi=10.1002/dev.420050403 | pmid=4679817 | volume=5 | issue=4 | title=Mirror self-image reactions before age two | year=1972 | journal=Dev Psychobiol | pages=297–305 | author=Amsterdam B}}</ref><ref>{{cite book|url=https://books.google.com/books?id=7FK3AwAAQBAJ&q=Butterworth%2C+1992&pg=PA94|title=Self-awareness in the first few weeks of life|access-date=4 November 2017|isbn=9781136872006|last1=Brown|first1=Jonathon|date=2014-06-03|publisher=Psychology Press }}</ref><ref>Social Psychology, 6th Edition p. 68-69</ref> Animals,<ref name="coren">{{cite book |title=How Dogs Think |author=Stanley Coren |isbn=978-0-7432-2232-7 |year=2004 |publisher=Free Press |url-access=registration |url=https://archive.org/details/howdogsthinkunde00core }}</ref> young children,<ref name="palmer">{{Cite web|url=https://www.ulm.edu/~palmer/ConsciousnessandtheSymbolicUniverse.htm|title=Consciousness and the Symbolic Universe|website=ulm.edu}}</ref> and people who have gained sight after being blind from birth,<ref name="archer">{{cite book |last=Archer |first=John |year=1992 |title=Ethology and Human Development|publisher=Rowman & Littlefield |isbn=978-0-389-20996-6}}</ref> sometimes react to their reflection in the mirror as though it were another individual.{{Citation needed|date=December 2014}}

Theorists have remarked on the significance of this period in a child's life. For example, [[psychoanalyst]] [[Jacques Lacan]] used a similar test in marking the [[mirror stage]] when growing up.<ref name="Lacan">Lacan, J., ''Some reflections on the Ego'' in ''Écrits'', org. published 1949.</ref> Current views of the [[self (psychology)|self in psychology]] position the self as playing an integral part in human motivation, cognition, affect, and [[social identity]].<ref name="Sedikides" />

==Robots==
In 2012, early steps were taken to make a [[robot]] pass the mirror test.<ref>{{Cite news | url=https://www.bbc.com/news/technology-19354994 | title=Robot learns to recognize itself| publisher=BBC News| date=2012-08-23}}</ref>

==See also==
* [[Animal consciousness]]
* [[Cognitive tests]]
* [[Embodied cognition]]
* [[Face perception]]
* [[Self-agency]]
* [[Visual perception]]
* [[Visual system]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20250130072513/https://www.animalcognition.org/2015/04/15/list-of-animals-that-have-passed-the-mirror-test/ List of animals who passed the mirror test and promising candidates on animalcognition.org (Wayback Machine)]
* [https://web.archive.org/web/20090203193304/http://www.mimed.mw.tum.de/06-12-18_MIMED_LUETH-002918.PDF The World First Self-Aware Robot and the Success of Mirror Image Cognition] (Lecture at the Karlsruhe University and the Munich University, Germany), 8 November 2006.
* [https://www.theguardian.com/uk_news/story/0,,1935538,00.html Elephants pass mirror test of self-awareness (The Guardian)]
* [http://news.bbc.co.uk/1/hi/sci/tech/6100430.stm Elephants' jumbo mirror ability (BBC News)]
* {{cite journal |last1=Plotnik |first1=Joshua M. |last2=Waal |first2=Frans B. M. de |last3=Reiss |first3=Diana |title=Self-recognition in an Asian elephant |journal=Proceedings of the National Academy of Sciences |date=7 November 2006 |volume=103 |issue=45 |pages=17053–17057 |doi=10.1073/pnas.0608062103 |pmid=17075063 |pmc=1636577 |bibcode=2006PNAS..10317053P |doi-access=free }}
* [https://www.newscientist.com/article/dn10402-elephants-see-themselves-in-the-mirror.html Elephants see themselves in the mirror (Newscientist.com with video])
* [http://www.conscious-robots.com/2010/01/08/can-a-robot-pass-the-mirror-test/ Can a robot pass the mirror test? – Raúl Arrabales Moreno], 2010-01-08
* {{cite journal |last1=Baragli |first1=Paolo |last2=Scopa |first2=Chiara |last3=Maglieri |first3=Veronica |last4=Palagi |first4=Elisabetta |title=If horses had toes: demonstrating mirror self recognition at group level in Equus caballus |journal=Animal Cognition |date=2021 |volume=24 |issue=5 |pages=1099–1108 |doi=10.1007/s10071-021-01502-7 |pmid=33713273 |pmc=8360890 }}

{{animal cognition}}

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[[Category:Cognitive tests]]
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