What the Mirror Test Actually Is
Gordon Gallup Jr. put a chimpanzee in front of a mirror in 1970 and watched it do something no researcher had documented before: the chimp used the reflection to inspect parts of its own body it could not otherwise see, the inside of its mouth, the back of its ears. Gallup then anaesthetised the animal, painted a red mark on its forehead, and let it wake up. When the chimp saw its reflection, it reached up and touched the mark on its own face, not on the mirror. That touch was the test.
