20 Years Ago Scientists Asked People to Have Sex in an MRI Machine. Here's Why

Twenty years ago, a team of Dutch scientists published an odd-sounding journal article titled: "Magnetic resonance imaging of male and female genitals during coitus and female sexual arousal." The paper marked the first time people had been documented having sex inside a body scanner, and has become one of the most downloaded articles by The BMJone of the world's oldest and most prestigious medical journals.

The team's objective? To see if it was possible to take images of people's genitals while they had sex in a magnetic resonance imaging (MRI) scanner, and to test whether ideas at the time about the act were true.

Eight couples—including one pairing who were amateur street acrobats—and three single women took part in the study, which involved 13 experiments. Three couples had sex twice, and the single women achieved orgasm without a partner, according to the study.

Researchers recruited the participants "by personal invitation," they wrote in the study, and through a local scientific TV show. Presumably in order to ensure they could fit inside the snug MRI scanner tube, the volunteers were required to have small-to average weight and height.

Once they had found enough volunteers and gained their consent, the researchers asked them to visit a university hospital in the Netherlands.

The MRI scanner was positioned in a room next to a control room where researchers sat, with a curtain covering the window and the participants' modesty.

First, the women had their pelvises scanned while lying on their backs. Then the men were asked to enter the room and have sex in the missionary position. After this, the men were asked to leave and the women instructed to bring themselves to climax. The women let the researchers know when they were pre-orgasm, so they could snap an image. 20 minutes after the women achieved orgasm, researchers took the final image.

The men had more problems with sexual performance than the women, according to the researchers, and some took sildenafil—more commonly as Viagra—in order to maintain an erection.

Only one couple was able to have sex without Viagra. The authors wrote: "The reason might be that they were the only participants in the real sense: involved in the research right from the beginning because of their scientific curiosity, knowledge of the body, and artistic commitment.

"And as amateur street acrobats they are trained and used to performing under stress."

The team found that while having sex in the missionary position, the penis became boomerang-shaped, and a third of its length consisted of the root of the penis. When the women were aroused, their uteri appeared to raise and their vaginal walls lengthened.

The researchers wrote: "It took years, a lobby, undesired publicity, and a godsend (two tablets of sildenafil 25 mg) to obtain our images. They show that such pictures are feasible and add to our knowledge of anatomy."

"What started as artistic and scientific curiosity has now been realized," they said.

In 2000, the study won an Ig Nobel award, which is given to research that makes readers laugh, then think.

Dr. Tony Delamothe, who retired as the deputy editor of The BMJ in 2016, wrote about the study's anniversary and its popularity in this year's Christmas issue of the journal.

No one believed the study was particularly useful clinically or scientifically, but the editors thought it included images using new technology that readers might be interested in seeing, he said.

Delamothe suggested the study may have sparked so much interest because, though "it was hardly the medical equivalent of a moon landing," readers might have been excited by the prospect of seeing "coitus on screen" and for free.

"If that's the explanation, it's hard to think ourselves back to such an innocent age, given today's explicit online offerings," he wrote.

Delamothe, who also worked as The BMJ's web editor, recalled to Newsweek how the paper ended up in the journal's Christmas issue, which is when "quirky" papers are traditionally published in the journal. "Some scientists try very hard to get a paper into the Christmas BMJ, once in their lives," he said.

"When I was web editor we used to analyze which papers got the most 'hits' and publish a league table from time to time. To some of my colleagues' embarrassment, the MRI paper topped the table every time," said Delamothe.

Ida Sabelis, professor of organizational anthropology in Amsterdam, who took part in the study as well as working on it, told Delamothe her friends and family still find the work amusing "even though many are tertiary educated adults approaching retirement."

She said she finds the response "odd around the university, where her giggly colleagues are academics working in social sciences in one of the world's most progressive cities."

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A stock image shows a couple in bed. Getty