The mirror test measures animal self-awareness. To pass, a creature must recognise itself in a mirror. Only 13 species, including humans, have so far.
In the test, scientists place a coloured mark on an animal’s forehead and put it in front of a mirror. Some animals ignore the mirror, others consider it a different creature. A small few will adjust themselves while looking in the mirror and try to remove the mark. Such a response indicates they know the creature in the mirror is them, and act accordingly.
Gordon Gallup Jr. invented the test in 1970. He put chimpanzees in a room with a mirror. At first, they threatened their reflection but, after a time, started grooming and pulling faces. When Gallup put a red mark on one ear then removed the mirror, the chimpanzees continued to scratch and touch that ear. The test proves animal self-recognition and suggests self-awareness.
Animals that have passed:
- bottlenose dolphins
- Asian elephants
- Eurasian Magpies
- cleaner wrasses (a tropical reef cleaner fish)
Most gorillas fail the test. Eye contact is threatening for gorillas, so they may deliberately avoid looking at the mirror for long enough to recognise themselves.
Only one elephant, an Asian elephant in 2006 at Bronx Zoo, identified the X on its forehead after looking in a mirror. Elephant cognition evolved on a similar path to primates.
Magpies pass every time. The corvid family, which includes ravens and crows, have the same brain-body ratio as primates. While Eurasian magpies are among the most intelligent animals on the planet, their intelligence evolved from a different source than humans and primates.
In 1980, behavioural psychologist BF Skinner found pigeons could pass the test after extensive, scaffolded training. Untrained pigeons do not.
Human babies do not pass the test until between 12 and 24 months old. Studies show a discrepancy across different environments.
What do these creatures have in common? Animals that pass the test have a high body-brain ratio, advanced perception and cooperative social structures.
The mirror test is not the only indicator of self-awareness. Dogs, for example, rely on scent, so instantly discount any image from being them because of the lack of associated smell. That doesn’t mean they are necessarily self-aware, but if they were, a mirror-test wouldn’t tell you.
Without self-recognition, however, there cannot be self-awareness. Distinguishing the animals who pass from their peers is a significant step in unravelling the mystery of consciousness.
Sources: Animal Cognition, Brittanica, Science Daily.