...BUT THERE ARE ALSO FAR MORE THAN FIVE SENSES

WE ALL know about the five senses — but there are many more than that. We actually have anywhere between nine and 30-something, depending on the view of the scientist counting them.

They include proprioception — our sense of where our limbs are in space; it’s compromised when drunk, which is why people can’t walk in a straight line.

Kinaesthesia is the ability to sense movement, which is fooled when you sit on a motionless train, watch another one next to you pull out in the opposite direction, and for a second think you’re the one moving. And interoception is an awareness of internal sensations, such as hunger. Here are just a few of the astonishing secrets of our senses . . .

IS THE taste of a lemon fast or slow? Answer without thinking and I bet you said fast. I’ve asked the question to a room of 200 people and they’ve all shouted out ‘fast’ in unison. It’s an example of synaesthesia, where two or more senses are experienced together. Regardless of where they are in the world, people will more than likely agree that the taste of a lemon is fast and sharp, high-pitched and brightly coloured.

IN-FLIGHT food is made saltier to compensate for the noise of jet engines. That’s because loud background noise can dull our other senses. If you ate those meals at home, they would taste really salty.

THEY say ‘silence is golden’, but true silence can be terrifying. An ‘anechoic chamber’ is a room suspended on springs, its walls covered with an extreme version of the soundproof foam used in recording studios. All outside noise is nullified and the sound inside is dull and dead. If you spend a few seconds inside, you lose your sense of space and your balance starts to go. Then you start to hear the inner workings of your body — the pulse in your neck and the blood pumping around your ears becomes deafening. SMELL is a deceptively vital sense. Research at the University of South Carolina, shows that 76 per cent of people with anosmia — total loss of smell — suffer depression, anxiety, and feelings of vulnerability. This figure is way more than those who lose their hearing or sight.

HUMANS analyse personality by looking at another person’s face, and make judgments in as little as one-tenth of a second. Round features, big eyes and baby-like characteristics, for example, instinctively create trust. In a review of 506 small claims court hearings, researchers identified that people were more likely to win, whether they were plaintiff or defendant, if they were baby-faced or attractive — because of our innate visual prejudices.