So what does this mean for Hillary Clinton: caught, like so many women in politics, in a catch 22 whereby she has to be seen to look dominant and competent, without eschewing her femininity.

After the first televised debate at the end of September, Clinton was accused of having what was dubbed ‘Resting Hillary Face’, for her tendency to let her disdain for her opponent shine through on her face rather than in her speeches.

A play on the term Resting B*tch Face, which is applied to any woman who fails to look sunny and amenable 24/7, it is also, Dr DeBruine explains, a label which tends only to be applied to women, whom society expect to appear warm and open.

Clinton can’t win. Too stern, and she’s seen as bossy and grumpy; too smiley and she’s false or weak. In the last debate she was even deemed part-automaton for failing to flinch when a fly landed on her face. “PROOF! She’s a robot!” screamed the Internet.