Humans like to regard themselves as exceptional. Many philosophers believe humans are the only
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which understands that others have their own personal thoughts. That understanding is known in the
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as having a "theory of mind," and it is considered the
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to such cherished human
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as sympathy and deception.
Biologists have learned to treat such
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with caution. Bernd Heinrich and Thomas Bugnyar describe an experiment they have carried out
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ravens.
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to gaze is reckoned to be a good
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of the development of theory of mind in human children.
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about 18 months, most children are able to follow the gaze of another person, and
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things about the gazer from it. Failure to
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this trick is an early symptom of autism, a syndrome whose main underlying feature is a(n)
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to understand that other people have
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, too.
To
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whether ravens could follow gaze, Dr Heinrich used six six-month-old hand-reared ravens. The birds were set, one at a time, on a perch on one side of a room divided by a barrier. An experimenter in front of the barrier
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his head and eyes in a particular
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and gazed for 30 seconds before looking
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. Dr Heinrich found that all the birds were able to follow the gaze of the experimenters, even
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the barrier. In the
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case, the curious birds either jumped down from the perch and walked around the barrier to have a
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or leapt on top of it and peered over.