What do humans, great apes, orcas, bottlenose dolphins, Asian elephants and Eurasian magpies have in common? They can all, unlike all other animals studied, recognise themselves in a mirror. Now, neuroscientists are claiming rhesus monkeys should join that exclusive self-aware club. But, there’s a caveat: the monkeys have to be trained.
Using the mirror self-recognition test, where an odourless, non-irritant dot is covertly placed on a subject's face, researchers from the Institute of Neuroscience at the Chinese Academy of Sciences hoped to conclusively prove that rhesus monkeys are self-aware.
The monkeys were trained to use a mirror as an instrument to find hidden objects. The monkeys were fixed into a special seat to ensure they looked forward at a mirror. A red laser pointer was then shone on an adjacent board that could be seen in the mirror. The monkeys successfully touched the dot on the board, showing awareness that they were touching something reflected in the mirror.
Once this training was complete, the researchers introduced the self-awareness test. Now, the laser pointer was aimed at a monkey’s face, a location not used in the training. All three monkeys used in the study touched their face, both when in the test chair and when in their cages.
Importantly, the researchers note, the trained monkeys also showed “typical mirror-induced self-directed behaviours” in their cages. Left alone and unmarked, the monkeys inspected their genitals, opened their mouths to examine their teeth and combed their fur. It is, the researchers explain, a clear example that the monkeys both recognise themselves and know that they are looking at their own bodies. The control monkeys, who were not trained to understand how mirrors work, exhibited none of this behaviour when placed in front of a mirror.
A previous study carried out by the same researchers also found mirror self-recognition in rhesus monkeys after several weeks of training, but the results proved controversial. By directly training the monkeys to touch the dot, it was argued the experiment had simply trained the monkeys to act out a conditioned response. The new study, the researchers claim, dispels these doubts by only training the monkeys to use mirrors to find hidden objects.
The results, they continue, suggest that an initial failure to pass the mirror self-recognition test by many animals could be down to an inability to understand how mirrors work, rather than a lack of bodily self-consciousness. The work, led by Gong Neng, is published in the journal PNAS.
The major implication of the study is a basic flaw in the mirror self-awareness test. If an animal can’t understand what a mirror is and how it works, they will never complete the test. Similarly, if an animal mostly interprets the world in a non-visual way – through smelling, for example – then using a mirror to prove or disprove self-awareness is pointless.
A similar study, published in the journal PLOS One in September 2010, also found that rhesus monkeys recognise themselves in the mirror if given enough time to work out what a mirror is and how it works.
This article was originally published by WIRED UK
