Goosebumps are a universal physical phenomenon induced by thrills and chills. The hair-raising experience is a result of adrenaline stimulating minuscule muscles that pull at the roots of our arm hairs — in turn, making us bristle with bumps. This happens when we’re cold, when we’re emotional, and, according to a pre-print paper released Thursday in PeerJ, when some people just feel like it.

The ability to create goosebumps at will is called “voluntary piloerection.” It is very rarely documented: There are only three single-individual cases studies published about people with this talent, and scientists don’t have a clue how to explain it. To rectify this, an international team led by Northeastern University post-doctoral researcher James Heathers, Ph.D., recruited self-described “voluntary piloerecters” through a Facebook group and conducted the first systematic investigation into the sensational skill by having each participant answer a series of personal questions.

There were consistencies across the answers of all 32 respondents, Heathers and his colleagues write, though they kept in mind that the data they were using were all self-reported. The participants overwhelmingly described piloerection as a physical, deliberate act, like lifting their arm than trying to make themselves cry. Other voluntary piloerection techniques included the sensation of flexing a muscle in the brain, tightening a muscle behind an ear, and just thinking about doing it.

An example of voluntary piloerection.

Three-quarters of the respondents said that the goosebumps, once induced, began at the back of their head or neck, and 90 percent of the respondents said the goosebumps eventually showed up on their arms. Many of them discovered their skill as children, but some only realized they could do it after they came across the Facebook group and wanted to try it out. Despite those involved with the study, in general people with the skill are still very rare: In an attempt to test for the ability among 682 psychology students, the researchers found none of them were able to do it.

Voluntary piloerectors may have increased control over their goosebumps, but that’s not to say they’re completely divorced from the factors that drive goosebumps in the rest of us. Scientists reason that we get naturally get goosebumps when we’re scared or cold because it’s a survival technique that evolved as ancient humans’ bodies responded to fear and low temperatures by causing their body hair to stand on end, making individuals warmer and scarier-looking. Emotional experiences, like listening to music, gives us goosebumps too, and in some cases the “nice” goosebumps resulting from positive emotional experiences are referred to as a frisson or a skin orgasm — a rewarding effect of psychophysiological arousal.

Interestingly, three-quarters of the Facebook respondents in the study said that they deliberately triggered the bumps when they were engaging in an activity that naturally produces goosebumps for other people — emotional experiences like listening to music or having sex.

Though the study participants didn’t use emotion to trigger the bumps, the fact that they felt specific emotions after piloerection (in particular the feeling of awe), is evidence that some emotional connection remains. They also scored higher than average on a personality and emotion questionnaire testing for the trait of “openness”, which is in line with previous research showing that so-called “open” people are more likely to have involuntary goosebumps.

In a series of tweets on Thursday, Heathers admitted that while piloerectors’ goosebumps are definitely consciously controlled, it’s still hard to grasp how it’s possible. The muscles that cause goosebumps are smooth muscles, he says, so by definition there should be no conscious control over them. He and his team hope to study someone with the ability in person soon so they can explore how emotion plays into this voluntary choice.

And no — he can’t do it himself, and it’s very, very frustrating.

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