Travis Carrasco, 29, is a mechanical engineer in Las Vegas, Nevada. For all intents and purposes, he’s a normal individual. He loves coloring with colored pencils; likes leadership books and the color green.

But in youth, his relatives took notice of Carrasco’s peculiar tendency to sway his head back and forth. He told them he was giving himself goosebumps. They didn’t believe him.

They were wrong.

According to the low end of informal estimates, about one in every 1500 people have something called Voluntarily Generated Piloerection (VGP)—the ability to consciously give themselves goosebumps. The weird thing is, VGP shouldn’t exist. The phenomenon both perplexes and intrigues neurophysiologists by defying conventional understanding of how the unconscious nervous system operates.

A mammal’s hair follicle clings to the skin via a tiny muscle. When this muscle contracts, the hair will stand, the skin around it will undergo bump-shaped distortion, and voilagoosebumps.

For the 1499 people in this statistical metaphor, goosebumps are completely involuntary. The tiny muscle, called the arrector pili, is made of smooth muscle fibers. And like other smooth muscles of the body—those that handle digestion, blood flow, respiration, and so on—they are unconsciously regulated. The nerves attached to them lie in the autonomic nervous system, the part of the nervous system dedicated to managing bodily functions you aren’t supposed to control consciously, like heart rate or pupil dilation.

Voluntary Generated Piloerection "Shouldn't Be Possible"

When James Heathers, a physiologist at Northeastern University, came across an engineering paper referencing the only three single-individual case studies of VGP in medical history, he couldn’t believe it. 

“That was catnip for me,” Heathers tells Mental Floss, his voice cracking with excitement. “[VGP] shouldn’t be possible. That’s not how the autonomic nervous system works; what it does. This reason that it’s called autonomic—autonomos—it means ‘without thought.’”

Heathers, who normally spends his time in data science and patient-centered electronic health development, got to work on goosebumps as a scientific side-hustle. In 2018, he authored a paper in the journal PeerJ making the first published attempt at defining the prevalence and properties of VGP.

He wanted to know exactly how it works. What do people think about when they give themselves goosebumps? In what situations are they deployed? What personality traits are common in people with VGP?

Heathers sifted through obscure internet forums and sent out surveys, and ended up evaluating 32 participants with VGP using standardized personality tests. He found that those with VGP who responded to his survey had unusually ‘open’ personalities compared to the average person.

“They seem to be more creative; they imagine more,” Heathers says. “They pay more attention to themselves. They track their emotions more closely. They have a preference for new stuff … That’s either an artifact of people who are more open being more likely to answer a survey on the internet for fun, because they want to know about themselves; or it’s a component of the experience itself.”

A "Sixth Sense"

You may be thinking, Wait, I’m open-minded, and I can give myself goosebumps just by thinking of nails scratching a chalkboard. But Heathers is clear; that’s not VGP. 

“VGP has no mental or cognitive component,” Heathers says. “The vast majority of people who do it, in the way that we’ve defined it, simply have a really straightforward pathway. A lot of the time, they focus on a point, behind their ear or on their neck or at the back of the head. They don’t have to think of anything.”

In other words, those with VGP need only think about getting goosebumps—not about the situations that would, under normal circumstances, give them goosebumps.

“Basically, it starts at the base of my neck, the bottom of my head and the backside,” Carrasco, the engineer with VGP, tells Mental Floss. “When I trigger it, it feels like a bunch of sparks travel throughout my entire body, and I can do it repetitively, over and over and over and over and over. However, the strongest sensation is only the first couple times.”

While the induced goosebumps are stronger than those generated unconsciously, Carrasco says he can maximize the strength and resolution of his goosebumps by swaying his head from side to side.

“It’s a weird rhythm, but if I sway my neck, it triggers a really strong response,” Carrasco says. “You know when you squeeze your eyes really tight, and sometimes you hear pressure building, and it’s really just squeezing a muscle in your ears or your eyes. It’s similar to that, but when [the goosebumps] happen, sometimes I can hear that same pressure … it feels relaxing. It feels good.”

Carrasco likes to think it’s a sixth sense. He’s never met anyone else with VGP. But he notices that his son of 19 months sways his head a lot, too. And Carrasco can’t help but wonder, “Does he have the same ability I have?”

Maybe it’s genetic; scientists don't know. Whatever the cause, 30 to 40 times a week, you’ll catch Carrasco exercising his hidden superpower—a thought that just might give you goosebumps.