Hubbry Logo
Mirror testMirror testMain
Open search
Mirror test
Community hub
Mirror test
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Mirror test
Mirror test
Mirror test
View on Wikipedia
from Wikipedia

The hamadryas baboon is one of many primate species that has been administered the mirror test.

The mirror test—sometimes called the mark test, mirror self-recognition (MSR) test, red spot technique, or rouge test—is a behavioral technique developed in 1970 by American psychologist Gordon Gallup Jr. to determine whether an animal possesses the ability of visual self-recognition.[1] 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 it subsequently touches or examines the mark on its own body, this behavior is interpreted as evidence that the animal recognizes its reflection as an image of itself, rather than another animal.

The MSR test has become a standard approach for evaluating physiological and cognitive self-awareness. Few species have passed this test. However, several critiques have been raised that challenge the test's validity.[2][3] Some studies have questioned Gallup's findings;[2] others have discovered that animals exhibit self-awareness in ways not captured by the test, such as differentiating between their own songs and scents and those of others.[4]

Method and history

[edit]

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.[5] He also watched Jenny gaze into a mirror and noted the possibility that she recognized herself in the reflection.[6]

In 1970, Gordon Gallup Jr. experimentally investigated the possibility of self-recognition with two male and two female wild preadolescent chimpanzees (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.[1]

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.[7] 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:[8]

  1. social responses
  2. physical inspection (e.g., looking behind the mirror)
  3. repetitive mirror-testing behavior
  4. realization of seeing themselves

The rouge test was also done by Michael Lewis and Jeanne Brooks-Gunn in 1979 for the purpose of self-recognition with human mothers and their children.[9]

Implication and alternate explanations

[edit]

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[10] 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

[edit]

The MSR test has been criticized for several reasons, in particular because it may result in false negative findings.[11]

Perception

[edit]

It may be of limited value when applied to species that primarily use senses other than vision.[12][4][13] Humans have been determined by biologists to have some of the best eyesight amongst animals, exceeding the overwhelming majority in daylight settings, though a few species have better.[14] By contrast, dogs for example mainly use 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.[15][12] He tested his own dog, but his results were inconclusive.[16] Dog cognition researcher Alexandra Horowitz formalized Bekoff's idea in a controlled experiment, first reported in 2016[17] and published in 2017.[18] 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.[19] 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.[20] Dogs also show self-awareness in the size and movement of their bodies.[21] Garter snakes, a relatively social snake species, have also passed an odor based "mirror" test.[22]

Social motivation

[edit]

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.[23][24]

Disinterest

[edit]

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.[25] Similarly, lesser apes infrequently engage in self-grooming, which may explain their failure to touch a mark on their heads in the mirror test.[11] 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.[26]

Ambiguity

[edit]

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.[27]

Non-human animals

[edit]
European magpies 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.[28] Prevalence is about 75% in young adults and considerably less in young and aging individuals.[29]

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.[11]

Animals that have passed

[edit]

Mammals

[edit]
Cetaceans
[edit]
  • 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.[30][31]
  • Killer whale (Orcinus orca): Killer whales and false killer whales (Pseudorca crassidens) may be able to recognise themselves in mirrors.[32]
Primates
[edit]
  • Bonobo (Pan paniscus)[33][34]
  • Bornean orangutan (Pongo pygmaeus):[35] However, mirror tests with an infant (2-year-old), male orangutan failed to reveal self-recognition.[36]
  • Chimpanzee (Pan troglodytes):[1][37][38] However, mirror tests with an infant (11 months old) male chimpanzee failed to reveal self-recognition.[36] Two young chimpanzees showed retention of MSR after one year without access to mirrors.[39]
  • 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 gorillas failed to show self-recognition.[35][40][41][42] 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.[43][44] Gorillas who have passed the MSR were habituated to the mirror before testing and were not subject to anesthesia during the marking process.[45][46] Koko was among the gorillas who passed the MSR test under these circumstances.[43][44]
Proboscidea
[edit]
  • 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.[8] 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;[47] it was claimed this was because the mirror was too small.[8][48]
Rodents
[edit]

Birds

[edit]
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.[28] 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.[50]
  • 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.[51] 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.[52]
  • Some pigeons can pass the mirror test after training in the prerequisite behaviors.[53] In 1981, American psychologist B. F. Skinner found that pigeons are capable of passing a highly modified mirror test after extensive training.[54][55] In the experiment, a pigeon was 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, untrained pigeons have never passed the mirror test.[56]

Fish

[edit]
  • Bluestreak cleaner wrasse (Labroides dimidiatus): According to a study done in 2019, cleaner wrasses were the first fish observed to pass the mirror test.[57][58] 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. However, 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.[59][60][61] 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.[62] 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.[63][64] 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.[65]
  • 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).[66]

Crustaceans

[edit]
  • 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".[67]

Cephalopods

  • Mimic octopus (Thaumoctopus mimicus): A video in 2025 showed a Mimic Octopus recognising itself in a mirror.[68]

Insects

[edit]

Animals that have failed

[edit]

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

Mammals

[edit]
Carnivorans
[edit]
  • Sea lions (Zalophus californianus)[32][70]
  • 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.[71]
  • Dogs (Canis lupus familiaris): Dogs either treat the image as another animal, or come to ignore it completely.[72]
Primates
[edit]

Birds

[edit]

Fish

[edit]
  • 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.[80]

Cephalopods

[edit]
  • 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.[81]

Animals that may pass

[edit]

Mammals

[edit]
Primates
[edit]

Gibbon (g. Hylobates, Symphalangus and Nomascus) have failed to show self-recognition in at least two tests.[11][82] However, modified mirror tests with three species of gibbons (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.[83] Another study published in 2009 documents 12 cases of spontaneous self-recognition in front of the mirror by a pair of siamangs (Symphalangus syndactylus).[84] Capuchin monkey (Cebus apella) did not pass in one test[85] but recognized the reflection as special in another.[86]

Rhesus macaque (Macaca mulatta) Though macaques failed the original mark test,[1] they have been reported to exhibit other behaviours that indicate self-recognition.[87] 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.[88] It has been suggested this demonstrates at least a partial self-awareness, although further study is needed.[89]

Pigs
[edit]

Pigs 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.[90] BBC Earth also showed the food bowl test,[91] and the "matching shapes to holes" test, in the Extraordinary Animals series.[92]

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.[93]

Birds

[edit]

Adelie penguins do not react as if they would react to a wild bird, and when presented with a mirror, gestured to notice the reflection in the mirror. However, they were not bothered enough by the mirror-test marks on their face to react to the marks.[94]

Fish

[edit]

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.[66] 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.[95]

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.[96] 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°.[97]

Humans

[edit]
A human child exploring their reflection

The rouge test is a version of the mirror test used with human children.[98] Using 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.[99][100][101]

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.[102]

Developmental reactions

[edit]

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.[98] In another study, in 1974, at 18 months, half of children recognized the reflection in the mirror as their own.[99]

Self-recognition in mirrors apparently is independent of familiarity with reflecting surfaces.[100] In some cases, the rouge test has been shown to have differing results, depending on sociocultural orientation. For example, a 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.[103] A strong correlation between self-concept and object permanence have also been demonstrated using the rouge test.[104]

Implications

[edit]

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.[105][106][107] Animals,[12] young children,[108] and people who have gained sight after being blind from birth,[15] sometimes react to their reflection in the mirror as though it were another individual.[citation needed]

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.[109] Current views of the self in psychology position the self as playing an integral part in human motivation, cognition, affect, and social identity.[101]

Robots

[edit]

In 2012, early steps were taken to make a robot pass the mirror test.[110]

See also

[edit]

References

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Mirror test

View on Grokipedia
from Grokipedia
The mirror self-recognition test (MSR), commonly known as the mirror test or mark test, is a behavioral developed to evaluate whether non-human animals exhibit , interpreted as a potential indicator of or . In the standard procedure, an animal is briefly anesthetized and marked with an odorless, non-irritating dye on a body part (typically the face) that is visible only via reflection; upon recovery and mirror exposure, self-recognition is inferred if the subject investigates the mark on its own body—such as by touching or grooming it—rather than reacting to the reflection as a conspecific or ignoring it. Introduced by psychologist Jr. in 1970, the test first demonstrated positive results in chimpanzees (Pan troglodytes), where prolonged mirror exposure led to self-directed behaviors toward dye marks, suggesting they distinguished their reflection from others. This breakthrough established MSR as a benchmark for studying cognitive capacities across species, with subsequent adaptations applied to diverse taxa, including prolonged exposure phases to habituate subjects to the mirror before marking. Over decades, the test has revealed self-recognition in a select group of animals, primarily great apes like orangutans (Pongo spp.), gorillas (Gorilla gorilla), and bonobos (Pan paniscus), as well as humans beginning around 15–24 months of age. Beyond primates, robust evidence supports passage in non-primate mammals such as bottlenose dolphins (Tursiops truncatus), which spontaneously touch marks on their bodies after mirror exposure, and evidence of passage in Asian elephants (Elephas maximus), though results are mixed with only one individual clearly passing in the key study by using its trunk to explore head marks. More recently, a 2023 study found that laboratory mice (Mus musculus) passed using a tactile mark on the forehead. Avian species like the (Pica pica) have also passed by removing stickers from under their wings, marking the first non-mammalian success in 2008. More recent findings include cleaner wrasse fish (Labroides dimidiatus), which remove marks from their throats after mirror training, though this remains debated due to methodological variations. Rhesus macaques (Macaca mulatta) can pass with extensive video-mirror training, indicating that self-recognition may be latent but requires learning in some lineages. While MSR success is often equated with advanced , the test has faced criticisms for its potential anthropocentric , as it prioritizes visual self-perception and may overlook in species reliant on other senses like olfaction or in social contexts. Failures in species such as most monkeys, dogs, and cats do not conclusively rule out , and alternative paradigms—like body awareness tasks or subjective value assessments—have been proposed to broaden the evaluation. Nonetheless, the mirror test remains a foundational tool in , informing debates on the evolutionary origins of and in animals.

Introduction and Methodology

Definition and Procedure

The mirror test, also known as the mirror self-recognition (MSR) test, is a behavioral assay designed to evaluate an individual's ability to visually recognize itself in a reflection, distinguishing self from others. Developed by Jr. in 1970, the test probes for evidence of by observing whether a subject treats its mirror image as a representation of itself rather than an unfamiliar conspecific. The standard procedure consists of two main phases: habituation and the mark test. In the habituation phase, the subject is given extended exposure to its reflection in a mirror, typically over several days, to reduce initial social reactions such as aggression, avoidance, or affiliation directed toward the image as if it were another individual. Once habituated, the subject is briefly anesthetized, and an odorless, non-irritating mark—such as a spot of dye or paint—is applied to a body part that is visible only in the mirror (e.g., the forehead or ear in primates). After recovery, the subject is re-exposed to the mirror, and its behavior is systematically observed and recorded, often via video, for a set period (e.g., 5-10 minutes). Self-recognition is scored based on spontaneous, self-directed behaviors toward the mark, such as visually orienting to it, touching, rubbing, or attempting to remove it upon seeing the reflection, without prior or cueing. In contrast, is indicated by persistent social behaviors toward the (e.g., threats or grooming attempts directed at the reflection) or indifference to the mark, suggesting the subject does not associate the reflection with itself. Adaptations of the mark test have been developed for diverse species to account for sensory or anatomical differences. For instance, in non-mammalian animals like birds or , where visual cues may interact with other modalities, variations include using stickers on feathers or scales instead of , or substituting mirrors with video recordings of the marked subject to elicit self-directed responses. These modifications maintain the core principle of assessing contingency between the self and its representation while tailoring the method to species-specific perceptual capabilities.

Historical Development

The mirror test, also known as the mirror self-recognition (MSR) test, originated in 1970 when psychologist developed it during behavioral studies on chimpanzees at the Delta Regional Primate Research Center in , affiliated with . In his seminal experiment, Gallup anesthetized four young chimpanzees, applied odorless, non-irritating red dye marks to areas of their bodies (such as the eyebrow ridge and ) that were visible only via reflection, and then provided extended mirror exposure over several days before reintroducing the mirror post-anesthesia. The chimpanzees' subsequent self-directed behaviors, such as touching the marks while gazing into the mirror without tactile cues, indicated recognition of their reflected images as themselves, marking the first empirical demonstration of visual self-recognition in non-human animals. In the , Gallup and his collaborators expanded the protocol to other great apes, testing orangutans, , and to explore phylogenetic patterns of self-recognition. Orangutans demonstrated similar self-directed responses to marks, passing the test shortly after chimpanzees, while showed inconsistent results, often failing due to potential social or perceptual factors. These early extensions established the test as a benchmark for , with Gallup's ongoing research refining criteria for interpreting contingent behaviors like mirror-guided exploration. By the early , the method was adapted for human development; Beulah applied a version to infants aged 3 to 24 months, observing that self-recognition emerged around , aligning with broader milestones in theory of mind. Influential reviews by researchers like Mariska I. M. de Veer in the further scrutinized methodological variations, such as exposure duration and mark placement, to distinguish true self-recognition from learned responses in like . Key milestones in the 1990s and 2000s broadened the test beyond mammals, introducing applications to birds and prompting protocol adjustments. Although early attempts with pigeons in the 1980s involved training to elicit mark-directed behaviors, genuine self-recognition was first evidenced in Eurasian in 2008 by ethologist Helmut Prior and colleagues, who used yellow stickers on neck feathers and observed two of five birds removing marks only upon mirror exposure, suggesting independent of this capacity in corvids. The 2010s saw adaptations for aquatic species, with wrasse fish (Labroides dimidiatus) passing a modified mark test in 2019 through scraping behaviors targeted at blue marks under , verified via extensive mirror to rule out . Preliminary explorations in , such as in 2015, used video-recorded self-images and cleaning responses to marks, though results remain debated due to simpler sensory systems. Post-2020 refinements have shifted toward less invasive protocols to address ethical concerns and perceptual biases, incorporating digital and virtual elements. Studies on cleaner now employ photographs of the fish's own face alongside mirrors, confirming self-face recognition without physical marks and minimizing risks. Hidden-mark variants, using inert dyes or temporary alterations detectable only visually, have evolved to counter criticisms of olfactory cues. Recent 2024-2025 research on cleaner has further shown rapid acquisition of mirror self-recognition (within 12-50 minutes of exposure) and explored its evolutionary origins, reinforcing the test's applicability to while highlighting ongoing methodological debates. Gallup's continued advocacy has emphasized these updates, ensuring the test's robustness in probing evolution.

Theoretical Foundations

Implications for Self-Awareness

Passing the mirror self-recognition (MSR) test is interpreted as evidence of , where an individual can reflect on its own mental states, and a rudimentary , enabling distinction between self and others. This capacity aligns with higher-order consciousness in , echoing Descartes' as a foundation for self-reflective awareness and Nagel's inquiry into subjective experience, suggesting that self-recognition implies an "I" capable of beyond mere perception. In scientific terms, MSR signifies the ability to become the object of one's own attention, facilitating mentalistic attributions to oneself. From an perspective, self-recognition via the mirror test serves as a marker for complex , emerging in species navigating intricate where understanding others' perspectives enhances survival and . This connection underscores how likely co-evolved with , as evidenced by higher MSR success rates in gregarious species compared to solitary ones, supporting the social intelligence hypothesis that cognitive advancements like self-recognition arise from selective pressures in social environments. Gallup's hypothesis further integrates MSR with prosocial behaviors, positing that self-recognition correlates with and in social species, as the self-other distinction enables and targeted helping. Empirical support includes observations in and cetaceans, where MSR-positive individuals exhibit consolation and prosocial interventions, linking to the evolution of from to cognitive forms. However, passing the mirror test does not equate to full human-like ; it indicates a spectrum of rather than comprehensive , limited to bodily self-recognition without necessarily encompassing or autobiographical elements. Recent theoretical advances post-2020 emphasize multiple levels of , distinguishing bodily —assessed by MSR through visual-proprioceptive integration—from higher autobiographical self, which involves and future-oriented , suggesting a hierarchical model where mirror success represents an intermediate stage. As of November 2025, research on cleaner passing the MSR with ecologically relevant marks proposes that private may have originated in early ancestors, expanding its evolutionary scope beyond highly social mammals and birds.

Alternative Explanations

One prominent alternative explanation posits that animals passing the mirror test may be responding to the contingency between their own movements and the reflected image through associative learning, rather than recognizing the reflection as a representation of the . This view suggests that repeated exposure allows subjects to associate self-generated actions with the mirror's correlated responses, leading to self-directed behaviors like mark touching without implying . Another interpretation frames mark removal as tool-use or problem-solving, where the mirror serves as an aid to locate and eliminate an irritant or target on the body, independent of self-concept. A seminal demonstration of this came in a 1981 experiment with pigeons, in which birds were first conditioned to peck a blue dot on their breast visible only via mirror to obtain food rewards; upon later marking with an actual blue dot, the pigeons used the mirror to locate and remove it, mimicking self-recognition through training rather than innate understanding. Differences in mirror exposure across species or individuals can also account for passing behaviors, as prior familiarity with reflections may enable learned responses that simulate self-recognition without underlying . For example, rhesus macaques, which typically fail the test, exhibited mark-directed behaviors after video-training tasks that familiarized them with using reflections to identify targets on their bodies, suggesting that such abilities can emerge from extended exposure rather than an inherent trait. Empirical evidence further supports these alternatives, as various training protocols have induced "passing" in animals without evidence of genuine self-recognition; the pigeon study exemplifies how associative conditioning can produce test-compliant actions, while similar approaches in other species underscore the role of environmental learning over evolved self-awareness.

Criticisms and Limitations

The mirror self-recognition test is not the sole standard for assessing self-awareness; some scientists argue it may underestimate the abilities of certain species, and research in the field is ongoing.

Perceptual Challenges

One significant perceptual challenge in the mirror test arises from species-specific visual limitations, which can prevent animals from detecting the applied mark even if self-recognition occurs. Many animals possess dichromatic or tetrachromatic vision differing from human trichromatic capabilities, potentially rendering standard marks (e.g., red paint) invisible or inconspicuous; certain animals with visual spectra differing from humans may overlook marks placed on their bodies. Similarly, animals with restricted visual fields or lower acuity, such as certain birds or mammals, might fail to perceive the mark on non-facial areas due to anatomical constraints rather than a lack of self-awareness. These biases highlight how the test's reliance on human-centric visual cues can produce false negatives across taxa. Olfactory interference further complicates the mirror test for scent-dominant species, particularly mammals that prioritize smell over sight. In such animals, the absence of a conspecific odor from the mirror image may lead to dismissal of the reflection as non-threatening or irrelevant, causing them to ignore visual discrepancies like the mark despite potential self-recognition. This sensory mismatch underscores the test's bias toward visual processing, as olfactory cues often override or suppress visual responses in species like dogs or wolves, where smell guides social and environmental interpretation. Insufficient to mirrors exacerbates perceptual challenges in neophobic , where initial or avoidance of the novel stimulus hinders accurate assessment of self-recognition. Animals exhibiting strong neophobia, such as certain corvids or , may treat the mirror as a threat during short exposure periods, leading to avoidance behaviors mistaken for recognition failure; extended group habituation sessions have been shown to mitigate this by reducing anxiety and promoting exploration. In cases like Eurasian , neophobia combines with sensory preferences to limit engagement, emphasizing the need for prolonged acclimation to isolate perceptual responses from fear-driven ones. Species-specific adaptations, such as those in cephalopods, introduce additional perceptual ambiguities in the mirror test. Octopuses, for example, may respond to mirrors with body pattern changes resembling rather than self-directed mark removal, potentially mimicking awareness without true recognition; observed unilateral patterns and exploratory behaviors suggest reflexive visual processing tied to assessment or environmental blending. These adaptations complicate interpretation, as tactile or proprioceptive cues from marks can elicit responses independently of mirrors, blurring the line between perceptual detection and . To address these perceptual challenges, researchers have proposed species-tailored modifications, including multi-sensory tests that incorporate olfactory or tactile elements. The "olfactory mirror" test, for instance, presents self- versus other-odors to smell-reliant mammals, bypassing visual biases and revealing differential investigation of self-scents in species . Similarly, tactile marks—such as raised or scented stimuli—enable self-localization in visually impaired or non-visual species, as demonstrated in studies where touch facilitated reaching toward mirrored marks; multi-sensory integrations, combining visual, tactile, and olfactory cues, have shown promise in equines by promoting association of the reflection with bodily sensations. These adaptations aim to create ecologically valid assessments aligned with diverse sensory ecologies.

Behavioral Motivations

In gregarious species, social motivations can lead animals to interpret their mirror reflection as a conspecific, prompting aggressive or affiliative behaviors that mimic or mask true self-recognition. For instance, chimpanzees initially direct social gestures, threats, or play toward the , treating it as another individual in their group before transitioning to self-directed exploration, as observed in Gallup's foundational studies on . This response is driven by the species' need for social bonding or territorial defense, potentially delaying recognition of the reflection as self even if the cognitive capacity exists. Similar patterns occur in canids; wolves and dogs often exhibit territorial barking or investigative sniffing toward mirrors, interpreting the image as an intruder rather than a self-representation. Conversely, solitary or low-curiosity frequently fail the mirror test due to disinterest rather than a lack of , as they ignore the reflection entirely without engaging in investigation. Cats, tigers, and pumas—animals that interact minimally outside of —show little to no response to mirrors, avoiding prolonged exposure and thus never attempting to examine marks on their bodies. This behavioral disengagement stems from their solitary lifestyles, where from conspecifics are rare, reducing the motivational drive to respond to unfamiliar visual stimuli like a . Exploratory biases further complicate interpretations, as highly curious individuals may investigate novel marks on their bodies out of general inquisitiveness rather than self-recognition, coincidentally passing the test without understanding the reflection's relation to themselves. In , follow-up experiments by Gallup demonstrated that rhesus monkeys, after extended mirror exposure, began touching marks but only after reinforced exploratory touching, suggesting motivation and familiarity influenced outcomes more than innate . This highlights how innate can produce self-directed behaviors that resemble recognition but may not indicate a conceptual understanding of self. Age and prior experience also modulate motivation, with juveniles often lacking the drive to investigate mirrors or marks, leading to skewed failure rates across . Younger chimpanzees and dolphins exhibit reduced engagement with mirrors compared to adults, requiring repeated exposures to build interest before displaying potential self-recognition behaviors. In bottlenose dolphins, research revealed that play-oriented investigations of mirrors emerge earlier in juveniles than in humans or great apes, but initial disinterest in marks wanes with age and experience, underscoring how developmental stages affect motivational responses.

Test Ambiguities

One significant ambiguity in the mirror self-recognition (MSR) test arises from subjectivity in scoring self-directed behaviors, where researchers must interpret whether actions like glancing at a mark or fully touching it qualify as evidence of recognition. Variability in defining these criteria leads to inconsistent results across studies; for instance, methodological assessments of mark test protocols in revealed scores ranging from 2 to 10 out of 15, reflecting differences in how behaviors are categorized and quantified. This subjectivity is compounded by reliance on observational judgments without standardized thresholds, potentially inflating or underestimating self-recognition in species with subtle responses. Environmental and rearing confounds further complicate test interpretation, as human-influenced conditions can alter natural responses to mirrors. Animals raised in with frequent mirror exposure, such as pet dogs or lab-reared , often show habituated behaviors that mimic recognition but may not reflect innate , whereas individuals typically exhibit more social or agonistic reactions initially. In , for example, prior mirror exposure and rearing history significantly influence performance, with human-reared subjects more likely to pass due to familiarity rather than cognitive capacity. Recent 2025 field studies on chimpanzees using in-situ mark tests have shown failures without extensive training, further emphasizing how ecological and lack of prior exposure can confound results and question the test's assessment of innate . These factors introduce bias, as tests on domesticated or enriched animals may overestimate self-recognition prevalence compared to ecologically valid settings. The is also prone to false positives and negatives, undermining its reliability as a standalone measure. False positives occur when training induces mirror-guided behaviors without true self-recognition; in a seminal study, pigeons were conditioned through operant procedures to use mirrors to locate and remove marks on their bodies, passing a modified test despite lacking spontaneous recognition. Conversely, false negatives can arise from innate traits like , where animals fail to react to marks that blend with their natural coloration, masking potential . In cleaner wrasse , ecologically irrelevant or inconspicuous marks led to non-responses, whereas salient, parasite-mimicking marks elicited self-directed actions, highlighting how mark visibility affects outcomes. Inter-species comparability poses additional challenges, as the test's design assumes manipulable body parts and visual-motor coordination that vary widely across taxa. Standardizing the procedure is difficult for species with divergent body plans, such as insects lacking limbs for mark removal; attempts to adapt the test for honeybees, for example, rely on indirect measures like grooming responses, but these adaptations deviate from the classic protocol, complicating cross-taxa comparisons. A 2025 study on honeybees further illustrates these ambiguities, using modified grooming assays that highlight the challenges of homologous actions in invertebrates. Invertebrates like paper wasps show mirror-induced behaviors, yet the absence of homologous actions to primate touching prevents direct equivalence, leading to interpretive inconsistencies. Recent critiques since 2020 emphasize the need for composite assessments to address these ambiguities, advocating integration of the mirror test with other self-recognition assays like body awareness tasks. Studies on cleaner fish demonstrate that MSR passers accurately estimate their body size in spatial navigation tasks, suggesting a mental body schema that complements mirror results and provides a more robust indicator of self-representation. Similarly, ferrets and cats exhibit dimension awareness by adjusting passage through apertures, supporting calls for multi-method evaluations to capture self-awareness beyond visual cues alone. These approaches aim to mitigate methodological inconsistencies by triangulating evidence from diverse cognitive domains.

Results in Non-Human Animals

Mammals

Among mammals, several species from the order have demonstrated mirror self-recognition, beginning with chimpanzees (Pan troglodytes). In a seminal 1970 study, four chimpanzees were anesthetized and marked with odorless dye on parts of their bodies visible only in the mirror; upon recovery and exposure to the mirror, they used the reflection to touch and explore the marks on their own bodies, indicating recognition of the image as self rather than another individual. Similar behaviors were observed in orangutans (Pongo pygmaeus), where individuals marked on the face or ears directed exploratory actions toward the marks via the mirror after initial social responses to the reflection subsided. (Gorilla gorilla) show more variable results, passing the test under specific conditions such as reduced aversion to direct gaze or extensive prior mirror exposure; for instance, in controlled settings with mirrors integrated into enclosures, marked investigated the marks on their bodies using the reflection. Bonobos (Pan paniscus) also pass the mirror test, with individuals using the reflection to inspect body parts and exhibiting self-recognition behaviors, though prolonged mirror exposure may facilitate this ability similar to other great apes. Beyond primates, Asian elephants (Elephas maximus) passed the mirror test in a 2006 experiment involving three females exposed to a large mirror; after , they used the reflection to touch visible marks on their heads and trunks with their trunks, while ignoring marks on inaccessible body parts. Bottlenose dolphins (Tursiops truncatus) also exhibit self-recognition, as shown in a 2001 study where two dolphins, marked with black ink on various body parts, repeatedly positioned themselves to view and investigate the marks in the mirror, including areas like the jaw that they could not see directly. Killer whales (Orcinus orca) and false killer whales (Pseudorca crassidens) show evidence of self-recognition through mirror image processing, spending time viewing themselves and reducing social responses to the reflection, similar to dolphins, though a full mark test has not been conducted.

Birds

In birds, the (Pica pica) is the most robust example of mirror self-recognition. A 2008 study tested five magpies by applying a colored sticker to feathers above the under ; upon mirror exposure, three birds attempted to remove the mark by pecking at it or using their feet, demonstrating contingency checking and self-directed behavior rather than treating the reflection as a conspecific. Corvids like crows show ambiguous but supportive data; for example, New Caledonian crows (Corvus moneduloides) in a 2012 study engaged in mirror-guided tool use and reduced social displays, suggesting partial understanding of the reflection, though they did not consistently pass the mark test.

Fish

The bluestreak cleaner wrasse (Labroides dimidiatus) represents a rare case among , passing the mirror test in a 2019 study adapted for their . Fish were marked with or on the cover or throat while anesthetized; post-recovery, individuals with visible marks in the mirror spent more time inspecting those areas via the reflection and attempted to remove them, unlike controls without mirrors or with inaccessible marks. Follow-up work in 2022 confirmed this by varying mirror pre-exposure, reducing confounds and replicating self-directed mark removal. A 2024 study further showed that cleaner wrasse with MSR capacity can precisely estimate their body size based on a , supporting advanced self-representation.

Invertebrates

Evidence for self-recognition in invertebrates remains limited and tentative. Recent adaptations of the mirror test to olfactory modalities have explored like ants (Myrmica sabuleti), where in a 2015 study, marked ants groomed odor-altered body parts more frequently when exposed to a setup mimicking self-odor via chemical cues, suggesting possible self-discrimination, though visual mirror components were not fully conclusive. Broader olfactory mirror protocols proposed in 2018 for non-visual have not yet yielded definitive passes in . Across these taxa, that pass the mirror test tend to be highly social or exhibit large brain-to-body ratios, often displaying initial social responses to the mirror followed by self-directed exploration of marks, such as touching or grooming behaviors in and cetaceans. No confirmed new passers emerged from 2022-2025 studies, though ongoing research on elasmobranchs like manta rays (Mobula birostris) continues to investigate preliminary self-contingency checking.

Species That Fail

Among mammals, domestic dogs (Canis familiaris) consistently fail the visual mirror self-recognition (MSR) test, often exhibiting initial investigative behaviors such as sniffing or barking at the reflection, followed by or social-oriented responses rather than self-directed actions toward a mark. This failure is attributed to their reliance on olfactory cues over visual ones, making the test potentially unsuitable for scent-dominant species. Similarly, domestic cats (Felis catus) do not demonstrate self-recognition in mirrors; they typically display threat responses like hissing, swatting, or avoidance toward the image, treating it as a conspecific intruder without mark-directed behaviors. Most monkey species, including rhesus macaques (Macaca mulatta) and baboons (Papio spp.), fail the standard MSR test, showing aggression, threat displays, or social interactions with the reflection but no evidence of self-recognition in unmarked conditions; however, rhesus macaques can demonstrate self-recognition after extensive training. In birds, pigeons (Columba livia) do not spontaneously pass the classic MSR test, often ignoring the mirror or responding to it as a non-social stimulus without self-exploratory behaviors; while they can be trained to associate mirrors with rewards, this does not indicate natural self-recognition. Parrots, such as African grey parrots (Psittacus erithacus), generally fail as well, displaying exploratory pecking or social toward the reflection but lacking contingency checking or mark removal, though some individuals show prolonged viewing without self-directed responses. Most fish, including social cichlids like Neolamprologus pulcher, fail the MSR test by exhibiting avoidance, , or territorial displays toward the , without behaviors indicating recognition of a body mark or . These responses suggest the reflection is perceived as a rival rather than a . Cephalopods, particularly octopuses (Octopus vulgaris), have been tested in studies since the 2010s and fail to differentiate their mirror reflection from a conspecific, often responding with , ink release, or exploratory arm movements toward the image but showing no self-directed behaviors like mark investigation. Patterns in MSR failures frequently occur among solitary or less visually oriented species, where animals may treat the mirror as a or ignore it due to limited social in their natural , leading to aggressive or avoidant behaviors rather than self-exploration. Such outcomes highlight that test failures may stem from perceptual mismatches, like dominance of non-visual senses in scent-reliant animals, rather than absence of cognitive capacity.

Species with Inconclusive Results

Among mammals, in African lions, outcomes remain inconclusive due to social group effects, where dynamics and aggressive responses to perceived rivals complicate interpretation of mirror interactions as self-recognition. For birds, Clark's nutcrackers demonstrate graded responses in a modified mirror test involving food caching, suppressing caches more in the presence of a clear mirror than a blurry one or live observer, linking to but yielding ambiguous evidence for full self-recognition due to the lack of a standard marking procedure. Ambiguities in these results often stem from small sample sizes, variations in test protocols, and the need for further replication to distinguish self-recognition from other motivations. Current research from 2024-2025 includes preliminary mark tests on honeybees, using AI-assisted video analysis to evaluate borderline behaviors like mark inspection, though outcomes remain debated and require validation beyond stages.

Results in Humans

Developmental Milestones

Human infants generally exhibit no mirror self-recognition prior to 15 months of age, with the majority achieving it between 15 and 24 months, as evidenced by behaviors such as touching a visible mark on their own body that is imperceptible without the mirror. This timeline was established in foundational research by Amsterdam, in her study of mirror reactions in children under two years, observing that self-directed responses, like mark removal, emerge reliably around 18 months. The rouge test, involving a subtle mark (often red dye or a sticker) applied to the child's face or forehead without their knowledge, serves as the standard assessment method, with variations for toddlers including odorless, non-irritating substances to ensure safety and natural behavior. The progression of mirror self-recognition unfolds in distinct developmental stages. During the early stage (approximately 6-12 months), infants display joyful, social responses to their , such as smiling, vocalizing, reaching toward it, or treating it as a playmate or another baby, without recognizing it as themselves. At around 6 months, infants are often fascinated by their reflection, responding positively as to a social stimulus. Reactions may vary depending on the mirror's position (e.g., during tummy time or at different angles), as babies explore visually and socially, and such variations are typical and not concerning. This positive engagement occurs alongside the emergence of stranger anxiety around 6 months, a normal phase of attachment development in which infants become wary, clingy, or upset around strangers while perceiving their mirror image as a friendly social partner. In the middle stage (12-18 months), children treat the reflection as another individual, engaging in or contingent play, like waving or making faces in apparent . By the late stage (18 months and beyond), self-recognition solidifies, marked by self-directed actions toward the reflected mark, indicating an understanding that the image represents the self. Longitudinal studies tracking infants through the second year confirm this sequence, showing mirror self-recognition emerges alongside related skills like deferred and remains a stable marker of into adulthood, without reported declines in typically developing individuals. A 2024 study further showed that prompting infants to touch their faces promotes earlier self-recognition, highlighting the role of tactile-proprioceptive integration in this process. Several factors influence the timing and expression of these milestones. plays a key role, with infants demonstrating self-referential use (e.g., "me" or "mine") often coinciding with or preceding successful mirror recognition, suggesting verbal self-labeling reinforces visual . Parental affect-mirroring—where caregivers reflect the infant's emotions and actions—further supports this development by enhancing emotional self-attunement and sensorimotor integration. Cultural contexts also contribute to variations; for instance, children in autonomy-supporting societies (often Western) show higher pass rates on the rouge test by 24 months compared to those in more interdependent cultures, where self-recognition may appear later or less spontaneously due to differing emphases on . Recent research from the 2020s has illuminated the neural underpinnings, linking the emergence of mirror self-recognition to the maturation of the , particularly the medial prefrontal regions involved in self-referential processing and distinguishing self from others. Functional MRI studies of infants and toddlers reveal increased activation in these areas during self-recognition tasks, aligning with the cortical development that enables the cognitive shift around 18 months.

Cognitive Implications

Passing the mirror self-recognition test around 18 months of age signals the emergence of a subjective in human infants, coinciding with the onset of and the ability to form a coherent sense of over time. This milestone reflects a shift from egocentric to objective , where infants begin to distinguish their physical appearance from external representations, laying the foundation for more complex psychological processes like . In neurodevelopmental and neurodegenerative disorders, mirror test performance provides insights into disruptions in . Children with autism spectrum disorder (ASD) often exhibit delayed passage of the test, potentially indicating challenges in integrating sensory and for self-other differentiation, though this is debated as they typically succeed when matched for . Similarly, individuals with frequently fail self-recognition tasks, such as identifying themselves in a mirror, which correlates with progressive impairment in and a regression of akin to reversing early developmental stages. These findings underscore the test's utility in assessing how disorders erode the subjective self, with implications for distorted in conditions like , where chronic mirror avoidance or compulsive checking distorts self-perception. From an evolutionary standpoint, human proficiency in mirror self-recognition extends the limited self-awareness observed in great apes, such as chimpanzees, and is intertwined with the evolution of —the capacity to attribute mental states to oneself and others. This cognitive linkage suggests that self-recognition facilitated adaptive social behaviors in ancestral , enhancing and deception detection in group settings. Cultural contexts influence the timing and expression of self-recognition, with infants from individualistic societies, such as urban , demonstrating earlier mirror test passage compared to those from more interdependent, collectivist environments like rural , where relational self-concepts may prioritize body awareness over visual . In , achieving self-recognition also correlates with advanced social competencies, including heightened through emotional mirroring and the internalization of via sensitivity to societal norms and rules.

Applications to Artificial Intelligence

Testing in Robots

Adaptations of the mirror test for robotic systems typically involve virtual or simulated mirrors integrated into the robot's software environment, where "marks" are represented as discrepancies in the robot's digital self-model rather than physical alterations. These setups allow robots to visual feedback from a camera feed reflecting their physical form or a simulated avatar, prompting behaviors such as self-calibration of joint positions or simulated "removal" of the mark through adjustments. This approach tests whether the robot maintains an internal world model capable of distinguishing its own representation from external objects. Key studies in the 2000s and focused on to evaluate . In 2012, the Nico at demonstrated partial mirror self-recognition by inferring the position of a visual token on its arm from mirror reflections, using to map 3D space without explicit programming for . Similarly, a 2016 experiment with the simulator employed a blackboard architecture to enable the robot to monitor its body model and detect mirror contingencies, achieving recognition through modular control and perceptual monitoring. For in the , the EU-funded CoCoRo project (2011–2015) planned mirror experiments to assess whether an underwater swarm of autonomous vehicles could collectively discriminate its own mirrored image from another swarm, aiming to foster emergent at the group level, though full results were not realized. Criteria for passing the test in robots emphasize detection and response to discrepancies between the robot's predicted self-representation and the mirrored input, indicating an embodied internal model rather than mere reactivity. For instance, in a 2020 study, two passed an adapted by using deep auto-encoders to learn facial appearances and novelty detection to identify a simulated mark, triggering a reaching action via pre-learned joint mappings. The TIAGo mobile manipulator robot, in a 2019 experiment, recognized its reflection using probabilistic models to learn body under uncertainty, adapting to mirror perspectives without relying on for flexible self-perception. A 2021 implementation on a further advanced this by incorporating inner speech—a symbolic self-dialogue within an —to reason about perceptual signals and infer self from mirror images. Historically, early robotic attempts in the with simple reactive systems failed to exhibit contingency awareness, treating mirrors as novel stimuli without self-referential response. Progression in the 2010s and 2020s, driven by AI-integrated models in platforms like Nao and , enabled partial passing through learned self-models, shifting from programmed heuristics to emergent recognition via and cognitive architectures.

Challenges in AI Evaluation

The application of the mirror self-recognition test to encounters significant challenges stemming from the disembodied nature of most AI systems. Unlike biological organisms, which possess physical bodies capable of visual and tactile interaction with a mirror, many AI architectures—particularly large language models and non-embodied agents—lack a corporeal form, making direct application of the standard test infeasible. This limitation is exacerbated by the test's reliance on visual cues and physical marking, which do not align with AI's primarily computational or processing. Researchers note that traditional mirror tests provide only superficial or irrelevant insights for sophisticated AI, as self-recognition in machines may manifest through abstract reasoning or data simulation rather than perceptual embodiment. Adapting the test for AI often involves modifications like virtual environments or language-based proxies, but these raise validity concerns about whether they assess equivalent forms of . For embodied AI, such as , challenges include integrating sensory modalities beyond vision; a 2021 study demonstrated a passing an adapted mirror test via "inner speech" generation to infer its own appearance from observations, bypassing direct visual self-recognition but relying on pre-programmed internal modeling. This approach highlights the difficulty in distinguishing genuine from engineered simulation, as the 's success depended on explicit algorithmic inference rather than emergent . Seminal work by Gallup () on the original test for chimpanzees emphasized behavioral contingencies like mark-touching, yet AI adaptations struggle to replicate these without introducing anthropocentric biases. Interpretive ambiguities further complicate AI evaluation, as passing an adapted test may reflect data patterns or optimization artifacts rather than intrinsic . In conversational AI, self-recognition tasks—analogous to mirror tests—reveal inconsistencies, where models can describe their outputs as "self" in prompted scenarios but fail to maintain coherence across contexts, suggesting limited metacognitive depth. Moreover, the visual of the mirror paradigm overlooks non-visual self-recognition pathways in AI, such as auditory or proprioceptive analogs, potentially underestimating capabilities in diverse architectures. Recent adaptations have extended the test to large language models (LLMs) using text-based or visual prompt scenarios as of 2023–2024. For example, a 2023 proposed an "AI mirror test" for chatbots, where models like showed partial self-recognition by identifying their own generated text in simulated interactions, though results varied across models and prompts. Similarly, informal tests in 2024 on multimodal LLMs demonstrated emergent in some cases but highlighted failures in maintaining consistency, underscoring ongoing challenges in evaluating non-embodied AI. Ethical and methodological hurdles also arise, including the risk of over-attributing based on behavioral , which could mislead assessments of AI . Proposals for hybrid tests combining mirror-like simulations with theory-of-mind probes aim to address these gaps, but consensus remains elusive due to the test's origins in ethological research ill-suited for silicon-based intelligence.

References

  1. https://www.science.org/doi/10.1126/science.167.3914.86
  2. https://www.pnas.org/doi/10.1073/pnas.1701676114
  3. https://www.pnas.org/doi/10.1073/pnas.101086398
  4. https://www.pnas.org/doi/10.1073/pnas.0608062103
  5. https://www.nature.com/articles/s41598-024-70138-7
  6. https://www.cell.com/neuron/fulltext/S0896-6273(23)00933-9
  7. https://www.nature.com/articles/srep36459
  8. https://www.pnas.org/doi/10.1073/pnas.2208420120
  9. https://www.nature.com/articles/nature.2015.16692
  10. https://www.pnas.org/doi/10.1073/pnas.1620764114
  11. https://pmc.ncbi.nlm.nih.gov/articles/PMC9334443/
  12. https://link.springer.com/article/10.1007/s10071-021-01592-3
  13. https://psycnet.apa.org/record/2002-17539-040
  14. https://royalsocietypublishing.org/doi/10.1098/rstb.2024.0312
  15. https://psycnet.apa.org/record/2021-48424-001
  16. https://plato.stanford.edu/entries/self-consciousness/
  17. https://www.researchgate.net/publication/352115468_Implications_of_mirror_self-recognition_for_self-awareness
  18. https://pmc.ncbi.nlm.nih.gov/articles/PMC9881685/
  19. https://www.sciencedirect.com/science/article/abs/pii/S037663579700079X
  20. https://www.emory.edu/LIVING_LINKS/publications/articles/deWaal_2008.pdf
  21. https://pmc.ncbi.nlm.nih.gov/articles/PMC1636577/
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC10316713/
  23. https://pmc.ncbi.nlm.nih.gov/articles/PMC12612708/
  24. https://link.springer.com/article/10.1007/s11097-016-9486-7
  25. https://www.science.org/doi/10.1126/science.212.4495.695
  26. https://pmc.ncbi.nlm.nih.gov/articles/PMC8165164/
  27. https://onlinelibrary.wiley.com/doi/abs/10.1111/eth.12954
  28. https://www.wellbeingintlstudiesrepository.org/cgi/viewcontent.cgi?article=1159&context=acwp_asie
  29. https://pubmed.ncbi.nlm.nih.gov/29274762/
  30. https://www.sciencedirect.com/science/article/abs/pii/S0376635717300104
  31. https://pmc.ncbi.nlm.nih.gov/articles/PMC9876878/
  32. https://pmc.ncbi.nlm.nih.gov/articles/PMC9468443/
  33. https://pmc.ncbi.nlm.nih.gov/articles/PMC5433687/
  34. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0189813
  35. https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2022.951808/full
  36. https://pmc.ncbi.nlm.nih.gov/articles/PMC11750390/
  37. https://royalsocietypublishing.org/doi/10.1098/rspb.2024.1933
  38. https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001529
  39. https://www.biorxiv.org/content/10.1101/2025.10.14.682345v1
  40. https://www.mdpi.com/2076-2615/13/3/444
  41. https://www.sciencedirect.com/science/article/pii/S2589004224020248
  42. https://www.sciencedirect.com/science/article/pii/S0047248481800164
  43. https://link.springer.com/article/10.1007/BF02435514
  44. https://pmc.ncbi.nlm.nih.gov/articles/PMC7457926/
  45. https://pubmed.ncbi.nlm.nih.gov/11334706/
  46. https://pmc.ncbi.nlm.nih.gov/articles/PMC2517622/
  47. https://www.sciencedirect.com/science/article/abs/pii/S0003347211003307
  48. https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3000021
  49. https://pmc.ncbi.nlm.nih.gov/articles/PMC8853551/
  50. https://www.animalcognition.org/2015/04/15/list-of-animals-that-have-passed-the-mirror-test/
  51. https://www.sciencedirect.com/science/article/abs/pii/S0376635717304862
  52. https://www.researchgate.net/publication/297913466_Contingency_checking_and_self-directed_behaviors_in_giant_manta_rays_Do_elasmobranchs_have_self-awareness
  53. https://www.nature.com/articles/s41598-021-82309-x
  54. https://dogbehavior.it/dogbehavior/article/download/128/92
  55. https://pmc.ncbi.nlm.nih.gov/articles/PMC3046971/
  56. https://pubmed.ncbi.nlm.nih.gov/35771525/
  57. https://www.sciencedirect.com/science/article/abs/pii/S0944200621000507
  58. https://pubmed.ncbi.nlm.nih.gov/29150813/
  59. https://escholarship.org/content/qt0bk066tc/qt0bk066tc_noSplash_b5cc6fe1edd2b396794c68020172c59a.pdf
  60. https://pubmed.ncbi.nlm.nih.gov/6199243/
  61. https://pubmed.ncbi.nlm.nih.gov/4679817/
  62. https://www.parentingcounts.org/baby-begins-to-develop-self-awareness-15-24-months/
  63. https://raisingchildren.net.au/toddlers/behaviour/common-concerns/fear-of-strangers
  64. https://www.psy.uq.edu.au/~uqmniel1/pretence_self-recognition_imitation.pdf/
  65. https://pubmed.ncbi.nlm.nih.gov/38442709/
  66. https://pmc.ncbi.nlm.nih.gov/articles/PMC9272979/
  67. https://psycnet.apa.org/record/1996-07089-006
  68. https://pubmed.ncbi.nlm.nih.gov/23153268/
  69. https://pmc.ncbi.nlm.nih.gov/articles/PMC10742061/
  70. https://academic.oup.com/edited-volume/28365/chapter/215247846
  71. https://rke.abertay.ac.uk/files/15539930/Cunningham_MeInMemory_Accepted_2018.pdf
  72. https://pmc.ncbi.nlm.nih.gov/articles/PMC3223930/
  73. https://pubmed.ncbi.nlm.nih.gov/1430860/
  74. https://www.mayoclinic.org/diseases-conditions/body-dysmorphic-disorder/symptoms-causes/syc-20353938
  75. https://link.springer.com/article/10.1007/BF02437424
  76. https://www.sciencedirect.com/science/article/pii/S0003347299911661
  77. https://pubmed.ncbi.nlm.nih.gov/26825413/
  78. https://www.sciencedirect.com/science/article/abs/pii/S1053810012001225
  79. https://arxiv.org/abs/2011.04485
  80. https://scazlab.yale.edu/sites/default/files/files/HART-AAAI-12.pdf
  81. https://ceur-ws.org/Vol-1855/EUCognition_2016_Part12.pdf
  82. https://pdfs.semanticscholar.org/a3ee/19b2c247473a256bdcb7d8001c4fa209f6aa.pdf
  83. https://doi.org/10.1007/s13218-020-00701-7
  84. https://pal-robotics.com/blog/selfception-tiago-recognizes-itself-using-ai/
  85. https://www.[researchgate](/page/ResearchGate).net/publication/352771252_Robot_passes_the_mirror_test_by_inner_speech
  86. https://www.researchgate.net/publication/382424208_Manipulated_Mirror_Test_for_AI_Exploring_Self-Recognition_and_Adaptation_through_AI-Generated_Reflections
  87. https://arxiv.org/pdf/2002.02334
  88. https://www.theverge.com/23604075/ai-chatbots-bing-chatgpt-intelligent-sentient-mirror-test
  89. https://joshwhiton.substack.com/p/the-ai-mirror-test
  90. https://philarchive.org/archive/UMBNCS
Add your contribution
Related Hubs
User Avatar
No comments yet.