Volume 25, Issue 2, 19 January 2015, Pages 212–217
Report
- Referred to by
Animal Cognition: Monkeys Pass the Mirror Test
- Current Biology, Volume 25, Issue 2, 19 January 2015, Pages R64-R66
Highlights
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- We developed a novel training strategy to study mirror self-recognition in monkeys
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- Trained rhesus monkeys passed the conventional mark test in front of a mirror
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- Trained rhesus monkeys exhibited spontaneous mirror-induced self-directed behaviors
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- Rhesus monkeys may be useful for studying the origin of mirror self-recognition
Summary
Mirror
self-recognition is a hallmark of higher intelligence in humans. Most
children recognize themselves in the mirror by 2 years of age [1].
In contrast to human and some great apes, monkeys have consistently
failed the standard mark test for mirror self-recognition in all
previous studies [2, 3, 4, 5, 6, 7, 8, 9 and 10].
Here, we show that rhesus monkeys could acquire mirror-induced
self-directed behaviors resembling mirror self-recognition following
training with visual-somatosensory association. Monkeys were trained on a
monkey chair in front of a mirror to touch a light spot on their faces
produced by a laser light that elicited an irritant sensation. After
2–5 weeks of training, monkeys had learned to touch a face area marked
by a non-irritant light spot or odorless dye in front of a mirror and by
a virtual face mark on the mirroring video image on a video screen.
Furthermore, in the home cage, five out of seven trained monkeys showed
typical mirror-induced self-directed behaviors, such as touching the
mark on the face or ear and then looking at and/or smelling their
fingers, as well as spontaneously using the mirror to explore normally
unseen body parts. Four control monkeys of a similar age that went
through mirror habituation but had no training of visual-somatosensory
association did not pass any mark tests and did not exhibit
mirror-induced self-directed behaviors. These results shed light on the
origin of mirror self-recognition and suggest a new approach to studying
its neural mechanism.
Copyright © 2015 Elsevier Ltd. All rights reserved.
