Wikipedia
Trypophobia (from the , , meaning "hole" and , , meaning “fear”) is a proposed phobia (intense, irrational fear) of irregular patterns or clusters of small holes or bumps. The term is believed to have been coined by a participant in an online forum in 2005.
Trypophobia is not the name of a diagnosis in the American Psychological Association's Diagnostic and Statistical Manual, Fifth Edition (DSM-5) and it is rarely used in scientific literature, according to Jennifer Abbasi of Popular Science. Abbasi said, "professionals who study and treat phobias tend not to use all the Latin and Greek names that get tossed around on message boards and in the press." However, on blogs and in internet forums, thousands of people claim to have trypophobia. Psychiatrist Carol Mathews said, "There might really be people out there with phobias to holes, because people can really have a phobia to anything, but just reading what's on the Internet, that doesn't seem to be what people actually have." According to Mathews, most people writing online are likely disgusted by these types of images without meeting criteria for a real phobia .
Arnold Wilkins and Geoff Cole of the University of Essex's Centre for Brain Science were the first scientists to publish on the phenomenon. They believe the reaction is based on a biological revulsion, rather than a learned cultural fear. In a 2013 article in Psychological Science, Wilkins and Cole write that the reaction is based on a brain response that associates the shapes with danger. Shapes that elicit a reaction were said to include clustered holes in innocuous contexts such as fruit and bubbles, and in contexts associated with danger, such as holes made by insects and holes in wounds and diseased tissue such as those caused by mango worms in animals, especially dogs. Upon seeing these shapes, some people said they shuddered, felt their skin crawl, experienced panic attacks, sweated, palpitated, and felt nauseated or itchy. Some said the holes seemed "disgusting and gross" or that "something might be living inside those holes". Psychiatrist Carol Mathews believes that the responses are more likely from priming and conditioning.
A website, trypophobia.com, describes the phenomenon with videos and images. Images containing clusters of holes are presented in an arrangement that claims to rank the likelihood they will induce fear. Early images in the series include fruits such as oranges and pomegranates. Then, clusters of holes with a possible association with danger are presented, such as honeycombs, frogs, and insects and arachnids. Finally, images feature wounds and diseases. Using data from the site, Wilkins and Cole analyzed example images and believe that the images had "unique characteristics". They state that the reaction behind the phobia was an "unconscious reflex reaction" based on a "primitive portion of the brain that associates the image with something dangerous". In another research article, Le, Cole and Wilkins developed a symptom questionnaire that they say can be used to identify trypophobia.