Trypophobia is traditionally known as a fear of irregular patterns or clusters of small holes or bumps, such as those of a honeycomb, strawberry seeds, or even aerated chocolate. However, based on the findings of a new study, researchers at Emory University have found that the condition is driven less by fear and more by a feeling of disgust.
Although trypophobia is not officially recognized in the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders (DSM), the condition appears to be somewhat common.
“Some people are so intensely bothered by the sight of these objects that they can’t stand to be around them,” said Dr. Stella Lourenco, a psychologist at Emory University whose lab conducted the study. “The phenomenon, which likely has an evolutionary basis, may be more common than we realize.”
Prior studies have linked trypophobic reactions to viewing evolutionarily threatening animals. For example, the repeating pattern of high contrast seen in clusters of holes is similar to the pattern on the skin of many snakes and the pattern made by a spider’s dark legs against a lighter background.
“We’re an incredibly visual species,” says lead author Vladislav Ayzenberg, a graduate student in the Lourenco lab. “Low-level visual properties can convey a lot of meaningful information. These visual cues allow us to make immediate inferences — whether we see part of a snake in the grass or a whole snake — and react quickly to potential danger.”
It is well-established that looking at images of dangerous animals generally provokes a fear reaction in people. The heart and breathing rate goes up and the pupils dilate. This hyperarousal to potential danger is known as the fight-or-flight response.
For the new study, the researchers wanted to test whether this same physiological response was associated with seemingly innocuous images of holes.
They used eye-tracking technology to measure the pupil-size changes in participants as they viewed images of clusters of holes, images of threatening animals, and neutral images.
They found that, unlike images of snakes and spiders, the images of holes elicited greater constriction of the pupils, a response associated with the parasympathetic nervous system and feelings of disgust.
“On the surface, images of threatening animals and clusters of holes both elicit an aversive reaction,” Ayzenberg said. “Our findings, however, suggest that the physiological underpinnings for these reactions are different, even though the general aversion may be rooted in shared visual-spectral properties.”
So in contrast to a fight-or-flight response which sets the body up for action, a parasympathetic response slows heart rate and breathing and constricts the pupils.
“These visual cues signal the body to be cautious, while also closing off the body, as if to limit its exposure to something that could be harmful,” said Ayzenberg.
The researchers hypothesize that clusters of holes may be evolutionarily indicative of contamination and disease — visual cues for rotten or moldy food or skin marred by an infection.
Interestingly, the participants involved in the experiments were young people who did not report having trypophobia. “The fact that we found effects in this population suggests a quite primitive and pervasive visual mechanism underlying an aversion to holes,” says Lourenco.
Scientists have long debated the relationship between fear and disgust. The new study adds to the growing evidence that — while the two emotions are on continuums and occasionally overlap — they have distinct neural and physiological underpinnings.
“Our findings not only enhance our understanding of the visual system but also how visual processing may contribute to a range of other phobic reactions,” says Ayzenberg.
A third co-author of the study is Meghan Hickey. She worked on the experiments as an undergraduate psychology major, through the Scholarly Inquiry and Research at Emory (SIRE) program, and is now a medical student at the University of Massachusetts.
The findings of the study are published in the journal PeerJ.
Source: Emory Health Sciences