“Be careful what you click” — so begins the first lesson of Internet browsing. That link from a friend could very well be exactly what she says it is, but, then again, it might not be. You could end up watching Rick Astley singing his infamous one-hit wonder or, if your friend is really mean, watching something you’d really rather not see.

It’s unlikely that Charles Darwin had such things in mind when he first wrote about disgust in his 1872 work “The Expression of the Emotions in Man and Animals.” Here he noted his discovery that while different cultures may find different things disgusting, we all feel the emotion and express it in similar ways.

We’ve come a long way since Darwin’s time and, though there are likely benefits to studying and understanding disgust, experiments looking into the phenomenon often create a sense that scientists are trolling their subjects. 

A paper published in the science journal Public Library of Science in 2012 provides a good example.

For the study, scientists asked subjects to do some very disgusting things, such as sticking a needle into a cow’s eye, touching apparently used condoms or drinking juice from a cup with a large insect in it. While reading the study’s supplemental material, one can almost see the experimenters giggling with giddy joy as they come up with more and more gross tasks for participants to perform.

The study didn’t, however, just look at what scientists could get college students to do for a few bucks. Before asking them to perform the vile tasks, the scientists showed them one of three 35-minute film clips. One group watched a neutral movie, involving a train traveling through various landscapes. Another group watched exciting footage of river rafting and skydiving. And the third group watched “de Gast,” a female-friendly pornographic film whose title translates to The Guest — this study took place in the Netherlands, and the film is currently unavailable in the
United States.

The idea was to look at the effect sexual desire had on perception of disgust. Sex is pretty gross, what with all the saliva, sweat and body odors, which are “among the strongest disgust elicitors.” Indeed, as the authors note, looking at it objectively “raises the critical question of how people succeed in having pleasurable sex at all.” And, yet, our species wouldn’t survive without it. Perhaps there’s something about arousal — specifically sexual arousal, which is why the scientists also showed the river rafting video — which prevents the disgust impulse from taking hold.

The results confirmed the suspicion: Subjects, all female and heterosexual, were statistically more likely to perform disgusting tasks after watching “de Gast” than they were after watching the train video. And while the results suggest that they may have also been more likely to perform the tasks than those who watched the non-sexually arousing videos, the study was too small to confidently say that this difference was significant.

It’s possible that when this disgust mechanism isn’t properly repressed, it could lead to sexual dysfunction, which is one purpose for the study and a justification for funding it. But, though the scientists don’t explicitly say so in the paper, it’s hard to deny the main benefit, which is that it’s pretty funny. That fly in the juice gag never
gets old.