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You might think you know when something has made your hair stand on end, but a study shows we generally can鈥檛 tell whether or not we have goosebumps, or where on our body they are.

at Durham University, UK, and his colleagues聽. 鈥淭here鈥檚 very, very little research on them and it鈥檚 just fascinating because it鈥檚 one of those things that we鈥檙e so familiar with,鈥� says McPhetres. 鈥淥ne of the things that we noticed was that people are self-reporting goosebumps and we鈥檙e also watching goosebumps objectively on the camera, and they just don鈥檛 match. So we carried out a few other studies to look at this, because this is really strange.鈥�

The researchers filmed the thighs of 50 volunteers while they watched seven videos (see box below) that they have previously found to give most people goosebumps. While expressions such as 鈥渋t made my hairs stand on end鈥� or 鈥渋t gave me goosebumps鈥� are often used figuratively, the participants were asked to press a button when they thought they had goosebumps and hairs standing on end, known as piloerection, as opposed to merely feeling 鈥渃hills鈥� or other emotional responses.

The volunteers were seated at a desk, so were able to look at their arms to see if they had goosebumps, but it was hard for them to see their legs.

The team found that, in most cases, those with goosebumps that were visible on camera weren鈥檛 pressing the button, and vice versa.

In case the participants were getting goosebumps on, say, their thighs but not their arms, the researchers added another three cameras to monitor their arms and calves as well. They then tested another 40 volunteers, but the extra cameras made hardly any difference to the results.

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Overall, nearly 60 per cent of the total 90 volunteers did get piloerection and 50 per cent reported getting it, but only in a third of cases did the observed piloerection correspond with the participants鈥� reports, even though they were free to look at their arms to see if they had goosebumps.

Only 16 per cent of the volunteers did any better than would be expected when guessing, and not by much. 鈥淭he highest levels of accuracy were still not very accurate,鈥� says McPhetres.

In a follow-up online survey, an additional 500 people were asked where they get goosebumps when they get them. More than 40 per cent said on their forearms, yet the tests with multiple cameras showed that goosebumps appear at the same time on the arms and legs, rather than being limited to a specific site.

Our ability to know if we have piloerection is an example of what is known as interoceptive awareness. Other studies have linked poor awareness of what is happening physically to the body to poor mental health.

鈥淚 think people are just not very good at distinguishing between different physiological sensations,鈥� says McPhetres. 鈥淭here鈥檚 a lot that happens in your body, and it probably takes a level of acuity that we don鈥檛 possess to distinguish between chills and actual goosebumps.鈥�

Many mammal species use piloerection to protect themselves from the cold and to make themselves look bigger when threatened, such as cats raising their hackles. In people, it is no longer thought to have such an important role as most of our 鈥渇ur鈥� has become so fine that it isn鈥檛 usually visible. However, McPhetres says he has found that piloerection still raises skin temperatures in humans.