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Why do people scratch their heads when confused? © Getty Images

Why do people scratch their heads when confused?

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Carrying out an unrelated behaviour when unable to make a decision can soothe stress or warn others to give us some space.

Asked by: Sundus Ilott

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Head-scratching is an example of what biologists call a ‘displacement activity’, where an animal that’s unable to choose between two conflicting options will opt for neither and instead perform some unrelated behaviour. For example, a bird that’s unsure whether to attack or flee from a rival might suddenly begin to peck at the ground.

Originally, these behaviours – which can also include preening and grooming – may have emerged because the soothing physical contact, or the familiarity of a routine behaviour, acts to calm a stressed animal.

But the behaviours have evolved into part of the non-verbal language that animals use to signal their emotional state. A 2017 study at Portsmouth University found that macaques scratch their heads when stressed, and this acts as a signal that makes other macaques less likely to attack or harass them.

So we may have inherited this social cue from our ancestors, perhaps as a way of warning people to leave us alone when we’re thinking hard.

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Authors

luis villazon
Luis VillazonQ&A expert

Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.

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