Mirror test


The mirror test—sometimes called the mark test, mirror self-recognition test, red spot technique, or rouge test—is a behavioural technique developed in 1970 by American psychologist Gordon Gallup Jr. as an attempt to determine whether an animal possesses the ability of visual self-recognition. The MSR test is the traditional method for attempting to measure self-awareness. However, agreement has been reached that animals can be self-aware in ways not measured by the mirror test, such as distinguishing between their own and others' songs and scents. Conversely, animals that can pass the MSR do not necessarily have self-awareness.
In the classic MSR test, an animal is anaesthetised and then marked on an area of the body the animal cannot normally see. When the animal recovers from the anaesthetic, it is given access to a mirror. If the animal then touches or investigates the mark, it is taken as an indication that the animal perceives the reflected image as itself, rather than of another animal.
Very few species have passed the MSR test. Species that have include the great apes, a single Asiatic elephant, dolphins, orcas, the Eurasian magpie, and the cleaner wrasse. A wide range of species has been reported to fail the test, including several species of monkeys, giant pandas, and sea lions.

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. He also watched Jenny gaze into a mirror and noted the possibility that she recognised herself in the reflection.
In 1970, Gordon Gallup, Jr., experimentally investigated the possibility of self-recognition with two male and two female wild preadolescent chimpanzees, 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 behaviours was recorded upon introducing the mirrors to the chimpanzees. Initially, the chimpanzees made threatening gestures at their own images, ostensibly seeing their own reflections as threatening. Eventually, the chimps used their own reflections for self-directed responding behaviours, such as grooming parts of their body previously not observed without a mirror, picking their noses, making faces, and blowing bubbles at their own reflections.
Gallup expanded the study by manipulating the chimpanzees' appearance and observing their reaction to their reflection in the mirror. Gallup anaesthetised the chimpanzees and then painted a red alcohol-soluble dye on the eyebrow ridge and on the top half of the opposite ear. When the dye dried, it had virtually no olfactory or tactile cues. Gallup then returned the chimpanzees to the cage and allowed them to regain full consciousness. He then recorded the frequency with which the chimpanzees spontaneously touched the marked areas of skin. After 30 minutes, the mirror was reintroduced into the room and the frequency of touching the marked areas again determined. The frequency of touching increased to four to ten, with the mirror present, compared to only one when the mirror had been removed. The chimpanzees sometimes inspected their fingers visually or olfactorily after touching the marks. Other mark-directed behaviour included turning and adjusting of the body to better view the mark in the mirror, or tactile examination of the mark with an appendage while viewing the mirror.
An important aspect of the classical mark-test is that the mark/dye is nontactile, preventing attention being drawn to the marking through additional perceptual cues. For this reason, animals in the majority of classical tests are anesthetised. Some tests use a tactile marker. 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 recognise themselves in a mirror typically progress through four stages of behaviour when facing a mirror:
Gallup conducted a follow-up study in which two chimpanzees with no prior experience of a mirror were put under anesthesia, marked, and observed. After recovery, they made no mark-directed behaviours either before or after being provided with a mirror.
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.

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 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".

Animals that have passed

Several studies using a wide range of species have investigated the occurrence of spontaneous, mark-directed behaviour when given a mirror, as originally proposed by Gallup. Most marked animals given a mirror initially respond with social behaviour, such as aggressive displays, and continue to do so during repeated testing. Only a few species have touched or directed behaviour 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. Prevalence is about 75% in young adults and considerably less in young and aging individuals.
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 behaviours or traits, although species arrive at them by different routes, and the underlying mechanism may be different.

Mammals

Cetaceans

A range of species have been exposed to mirrored surfaces. While these species may have failed the classic MSR test and studies may not have taken into account human-shyness of each organism, they have shown mirror-related behaviour:

Mammals

Gorillas

Findings for gorillas are mixed. At least four studies have reported that gorillas failed the MSR test. The gorilla may be the only great ape that "lacks the conceptual ability necessary for self-recognition". Other studies have found more positive results but have tested gorillas with extensive human contact and required modification of the test by habituating the gorillas to the mirror and not using anaesthetic. Koko reportedly passed the MSR test, but this was without anaesthetic. In gorillas, protracted eye contact is an aggressive gesture and they may, therefore, fail the mirror test because they deliberately avoid making eye contact with their reflections. This could also explain why only gorillas with extensive human interaction and a certain degree of separation from other gorillas and usual gorilla behaviour are more predisposed to passing the test.

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 behaviours when exposed to the mirror. Manta rays have the largest brains of the fishes. In 2016, Dr. 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.
Another fish that may pass the mirror test is an 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. 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°. This is an impressive task for a fish, so the archerfish could be worth testing in the mirror task, since it has already succeeded in a different visual task.

Pigs

s can use visual information seen in a mirror to find food, and show evidence of self-recognition when presented with their reflections. In a 2009 experiment, seven of the eight pigs tested were able to find a bowl of food hidden behind a wall and revealed using a mirror. The eighth pig looked behind the mirror for the food. BBC Earth also showed the foodbowl test, and the "matching shapes to holes" test, in the Extraordinary Animals series.

Robots

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

Criticism

The MSR test has been criticised for several reasons, in particular because it may result in false negative findings.
The MSR test may be of limited value when applied to species that primarily use senses other than vision. For example, dogs mainly use olfaction and audition; 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. He tested his own dog, but his results were inconclusive. Dog cognition researcher Alexandra Horowitz formalized Bekoff's idea in a controlled experiment, reported in 2016 and published in 2017. 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. A 2016 study suggested an ethological approach, the "Sniff test of self-recognition " which did not shed light on different ways of checking for self-recognition.
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 to calmly consider what the reflection actually represents. This may be why gorillas and monkeys fail the MSR test.
In a 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 recognise themselves. For example, in a MSR test conducted on three elephants, only one elephant passed the test, but the two elephants that failed still demonstrated behaviours 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. Similarly, lesser apes infrequently engage in self-grooming, which may explain their failure to touch a mark on their heads in the mirror test.
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.
Finally, controversy arose over whether self-recognition implies self-awareness. The ant researchers state that many ants, from three species, pass the mirror test, but the researchers do not know that they have self-awareness. Dogs recognize their own scent as different from others' scents, but fail the traditional, visual mirror test.

Rouge test

The rouge test is a version of the mirror test used with human children. 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.

Developmental reactions

From the ages of 6 to 12 months, the child typically sees a "sociable playmate" in the mirror's reflection. Self-admiring and embarrassment usually begin at 12 months, and at 14 to 20 months, most children demonstrate avoidance behaviours. Finally, at 18 months, half of children recognise the reflection in the mirror as their own and by 20 to 24 months, self-recognition climbs to 65%. Children do so by evincing mark-directed behaviour; they touch their own noses or try to wipe the marks off.
Self-recognition in mirrors apparently is independent of familiarity with reflecting surfaces. 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 and mutual eye contact. A strong correlation between self-concept and object permanence have also been demonstrated using the rouge test.

Implications

The rouge test is a measure of self-concept; the child who touches the rouge on his own nose upon looking into a mirror demonstrates the basic ability to understand self-awareness. Animals, young children, and people who have their sight restored after being blind from birth, sometimes react to their reflection in the mirror as though it were another individual.
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. Current views of the self in psychology position the self as playing an integral part in human motivation, cognition, affect, and social identity.

Methodological flaws

There is some debate as to the interpretation of the results of the mirror test, and researchers in one study have identified some potential problems with the test as a means of gauging self-awareness in young children and animals.
Proposing that a self-recognising child or animal may not demonstrate mark-directed behaviour because they are not motivated to clean up their faces, thus providing incorrect results, the study compared results of the standard rouge test methodology against a modified version of the test.
In the classic test, the experimenter first played with the children, making sure that they looked in the mirror at least three times. Then, the rouge test was performed using a dot of rouge below the child's right eye. For their modified testing, the experimenter introduced a doll with a rouge spot under its eye and asked the child to help clean the doll. The experimenter would ask up to three times before cleaning the doll themselves. The doll was then put away, and the mirror test performed using a rouge dot on the child's face. These modifications were shown to increase the number of self-recognisers.
The results uncovered by this study at least suggest some issues with the classic mirror test; primarily, that it assumes that children will recognise the dot of rouge as abnormal and attempt to examine or remove it. The classic test may have produced false negatives, because the child's recognition of the dot did not lead to them cleaning it. In their modified test, in which the doll was cleaned first, they found a stronger relationship between cleaning the doll's face and the child cleaning its own face. The demonstration with the doll, postulated to demonstrate to the children what to do, may lead to more reliable confirmation of self-recognition.
On a more general level, it remains debatable whether recognition of one's mirror image implies self-awareness. Likewise, the converse may also be false—one may hold self-awareness, but not present a positive result in a mirror test.