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

Why do people scratch their heads when confused?

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

Advertisement

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.

Read more:


Advertisement

Subscribe to BBC Science Focus Magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun facts.