Julia was around 11 years old the first time it happened. She let herself into her dad’s apartment in Malmö, Sweden, dropped her schoolbag and flopped on to the sofa. She switched on the TV and turned to her favourite channel in time for the cartoons. The screen filled up with a cartoon man with a huge head. On his chin, in place of skin or a beard were huge cracks. Suddenly, she felt like she was going to throw up in disgust. She screwed up her eyes and fumbled for the button to turn off the TV.

Every few months or so after this, she would see something that she just could not bear. Something that made her feel utterly disgusted and terrified. Sometimes it was cracks, but other times it was patterns of holes or dots, or scenes from nature programmes showing things such as groups of barnacles. She would shake, pour with sweat and end up lying on the floor in tears. One time, she was chatting on the phone when she saw something so awful she threw her mobile across the room. No one else she knew seemed to have this strange reaction. What was going on?

Then, one day, when she was living in London in her early 20s, her then-boyfriend came bursting through the front door after work. “Julia!” he shouted. “I know what you have!”

Trypophobia is an aversion to clusters of holes or cracks that is associated with feelings of fear and disgust. You might not have heard of it. But do not worry: you won’t be able to forget it now. Psychologists recognise a number of phobias that can have a huge negative impact on people’s lives. The new kid on the block, trypophobia, is not yet widely accepted as one of them. There is even debate about whether it is a phobia at all, because while most phobias are synonymous with abject terror, a number seemingly provoke disgust as well as fear. Some researchers think that trypophobia is based only in disgust.

Asked what first triggered their trypophobia, people describe everything from a Christmas bauble to a picture of a wasps’ nest, pitted bricks in a wall, bubbles in cake batter, or the way water beaded on their shoulder after a shower. As well as such triggering objects in real life, many trypophobes describe images as being particularly problematic. Pictures involving lotus seed pods are often cited as initial triggers. The lotus plant produces large green seed heads that look almost like a shower head, with many large seeds. The “lotus boob” meme, a fake image and story about an infected breast, caused quite the stir when it started circulating on email back in 2003.

There is limited research into trypophobia, but one study might help explain why that meme (debunked by the fact-checking website Snopes) spread so far and wide – it found that trypophobia is more powerful when holes are shown on skin than on non-animal objects such as rocks. The disgust is greater when holes are superimposed on faces.

Of course, the lotus boob meme would not have gone anywhere without the internet. The web has been linked to the rise of other conditions that have physical or behavioural symptoms but, many believe, have their origin in the mind – so-called psychogenic conditions.

From Strasbourg’s dancing plague of 1518 to the 2011 case of twitching teenage girls in a small town in New York state, mass psychogenic illnesses are nothing new. They are part of the fabric of being human. But with the internet and its virtually instantaneous global avalanche of information, billions of us can be exposed to potential triggers wherever we are in the world. And anyone with a device and an internet connection is a potential agent of spread. Online communities have emerged around things such as Morgellons disease (an unexplained skin condition) and people who believe they are “targeted individuals”, being stalked, surveilled or experimented on by the establishment. So, is trypophobia another of these odd conditions? Is it a product of the digital world, or simply disseminated through it? And why for the affected people are holes – of all things – the cause of utter terror?

Julia’s boyfriend grabbed his laptop and typed furiously into a search engine. He picked a video from the results and clicked play. She lasted 10 seconds before bursting into tears and running out of the room. The video was one of many you can find today that “tests” if you have trypophobia. They tend to be a series of triggering images – everything from lotus flower seeds to sponges. Once she had calmed down, Julia thought about what this moment meant. “I was really surprised, but also kind of happy,” she says. “It felt kind of comforting that other people had the same thing.”

There was just one catch. She couldn’t search online for more information because the first thing you see when you search “trypophobia” is triggering images.

Hence her boyfriend became her designated Googler, reading aloud anything he could find on the condition. This was also how Julia discovered and joined one of the two main Facebook groups for trypophobes.

Skimming through the groups, it does not take long to realise that trypophobia creeps into all aspects of life. People affected live in constant fear of being accidentally or deliberately triggered by any number of seemingly innocuous pictures or objects, from crumpets to brake-lights.

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A massage therapist tells me: “I can’t look at certain things … I have to send some clients away if they have triggering skin issues.”

“The hairs on my arms rise whenever I see MANY holes,” writes another person. “I would come to think that I’m gonna die if I keep on looking.” They are also troubled by anything with “hairy spikes”.

Talking about Facebook, one person says they are “always wondering if I’m about to get slammed in the eyes with pods, or holes in rocks.” They go on to describe watching TV or movies. “There are costume and makeup artists that love the effect for depth on screen. We’ll spend the rest of our viewing time knotted up …”

One user describes himself as a “6ft 4 big guy” who was “absolutely flattened” by one picture.

Online and in real life, trypophobic people say they are also deliberately shown triggering pictures by people looking to elicit a reaction. “It’s never going to be funny to surprise me with a photo of tiny holes etc,” writes one. “Making me panic is just cruel.” For these people, trypophobia is a question that no one wants to have to answer: what is in those holes?

The patient is gowned up. A dotted black felt-tip line marks the boundaries of the bump. The doctor chooses her weapon. “Ready?” she asks. Knife to skin. A disembodied gloved hand hovers nearby, holding gauze. Nearly. Nearly. Nearly.

Then it happens. A huge jet of oatmealy pus rises out of a shoulder cyst. A blackhead yields to the forces applied to it, dead-skin gunk snaking and coiling its way out of the pore like butter being squished through a cream cracker. It is gross and mesmerising.

I am weirdly fascinated by the US dermatologist Sandra Lee, AKA Dr Pimple Popper. She has 3.5 million followers on Instagram, 5.4 million on her YouTube channel, SLMD, and a TV series. Clearly, I am not alone.

I cannot stop watching her videos once I start. I get a taste in my mouth – thick, slightly metallic saliva. The headrush of anticipation, impatience, tension building up before the release. If you are not au fait, then pimple popping is the trend for filming, up close and personal, the act of popping, squeezing or otherwise removing blackheads, cysts and other dermatological dementors. It is disgusting. It is also ambivalent, not in the sense of indecision or ambiguity, but rather a strong tension between opposing forces – something that researchers in the field say is “equally capable of helping and harming, making laugh and making angry”. For me, pimple popping is gross, but it is also compelling. Try a video on your nearest and dearest. (Mother-in-law: loves it; colleague who sits dangerously near to my desk: not so much.) Anecdotally, pimple-popping seems to divide the trypophobia community down the middle too.

“They are surprisingly satisfying. I don’t know why,” says Julia, who is partial to the occasional popping video despite her trypophobia. Does she find them triggering? “A little bit, but only on the level that it’s still kind of nice. It’s a super-weird mix, like doing something you know that’s a bit dangerous but you kind of like it.”

What is in those holes? Pus, blood, gunk. Gross, but familiar. And being dealt with.

Think of the last time you were disgusted, I-need-to-bleach-my-brain-and-wash-my-hands-forever disgusted. Whenever it was, and whatever was behind it, we have something in common. The face that you would have made (and that you are probably making now, remembering) is the same as mine when I last stepped in warm cat sick. Your eyebrows contract, your eyes narrow, your nose wrinkles and your upper lip curls. That disgusted snarl is controlled by a muscle called the levator labii superioris – the movement of which is seen as the unique facial expression for disgust.

Researchers suggest that we have evolved disgust to help us avoid pathogens – things that can cause disease – found in everything from spoiled food to poisonous plants, from vomit to dead bodies. Faced with things we associate with disease or decay, we instinctively screw up our faces, to try to stop them entering our bodies through our mouth, nose and eyes. We retch, say “yuck”, and back off to protect ourselves from exposure to them and their disease-laden possibilities.

This pathogen-avoidance reaction is now being seen as a key part of what is called the behavioural immune system. This describes our thought processes and behaviours when we try to avoid parasites and infectious diseases. Tom Kupfer, an emotions researcher at Vrije Universiteit in Amsterdam, thinks that trypophobia is linked to our evolutionary adaptations to avoid parasites that live on our skin – things such as headlice and sand fleas. (Is it me, or is anyone else feeling itchy?)

Just as the typical disgust response evolved to stop us consuming things that could make us ill, skin-based responses like feeling itchy or that our skin is crawling may have evolved to protect us from these ectoparasites. In other words, our urge to scratch that itch is no different from a cow covered in flies swishing its tail, or a flea-ridden cat grooming itself.

A study co-led by Kupfer suggests that you do not need to feel parasites on your skin to get that response. “It looks like just those images [of parasites] can trigger the skin-protective response, even though that would normally be triggered by something actually crawling on your skin,” he says.

While people without trypophobia were grossed out by disease-related images such as ticks clustered on a dog’s ear, but not by images of innocuous things such as holes in bread, people with trypophobia reacted in exactly the same way to both sets of images. Kupfer suggests they could be overreacting in response to things that resemble pathogens or parasites but that are, in fact, harmless. Like someone scared of snakes getting a fright when they see a garden hose out of the corner of their eye.

As with pimple popping, there is an ambivalence within trypophobia. Some online support groups ban the posting of images that could trigger people, but over on Reddit, the subreddit for trypophobia is quite the opposite. As “ratterstinkle” told another user: “So the way it works in this sub is that people post pictures that trigger trypophobia.” This was in a thread called “That’ll do it”. Below was a phone screengrab showing a man with ragged, holey skin on his face.

Could clusters of holes actually appeal to some people? After all, there are tarantula-owners as well as arachnophobes; skydivers as well as people too terrified to climb up a stepladder. Perhaps. On Reddit there is a “trypophilia” subreddit, where one user asks, apparently rhetorically: “So, this is basically a mirror of /r/trypophobia with different captions? Am i missing something?”

On one of the two main trypophobia Facebook groups, one user explains their own love-hate relationship with trypophobic material: “Since I realised I wasn’t alone, I tried to desensitise myself to the images that affect me horribly. In trying to do that, I came across a YouTube video of a vet clinic in Gambia. Now I’ve become obsessed with watching their videos of a specific condition. I’m not exaggerating when I say I’m obsessed; it’s one of the first things I watch when I wake up. I have to watch it several times throughout the day.”

Another writes: “I almost feel drawn to look at the images of it because maybe my brain is telling me that if I look at it enough it will stop bothering me.”

There is a fair bit of discussion about this kind of exposure therapy in the online groups, especially given that forms of it are used to treat psychiatric issues including phobias, post-traumatic stress disorder and obsessive-compulsive disorder. However, there does not seem to be any published research on its success or not in treating trypophobia.

Some trypophobic people seek solace in another internet trend: autonomous sensory meridian response. ASMR has taken off big-time on YouTube. There are a reported 13m videos dedicated to it, designed to give viewers “brain tingles”. Fans of ASMR say it relaxes them and it can even beat insomnia. In April 2019, a New York hotel announced it was making in-room ASMR videos available for its guests. Classic ASMR fodder includes people eating, whispering, brushing hair, paper-crinkling, tapping and – somewhat curiously – the painting videos of the American TV artist Bob Ross.

There is an aspect of social contagion to these online communities, says Adrienne Massanari, associate professor in communication at the University of Illinois at Chicago. “You can easily share videos and gifs really quickly, and have this conversation that sort of takes you out of a sense of a solitary understanding of watching that video.”

With a couple of swipes and taps, the sender makes their experience of that little chunk of the internet a communal event. The sharing of such experiences is something Massanari calls “profoundly human”. We can feel this sense of connection even if the thing we’re sharing is something that seems revolting at first glance.

Julia doesn’t go online much, for fear of seeing something triggering. “It takes a long time to let go of it afterwards,” she says. She is careful about triggers offline, too. She loves TV and movies but will avoid anything that has underwater scenes in case she sees barnacles or animals with patterns of dots that look like holes. She doesn’t swim in the sea for the same reason – she stayed put on the boat during a family holiday in Egypt while her siblings enjoyed the water. She once made a friend change a jumper because it was full of holes and she couldn’t look at him.

She is a visual communication student and has the stunning Instagram you might expect: photos of skyscrapers, skylights, staircases. She even makes shopping trolleys and umbrellas beautiful – all stark angles, refraction and reflection, light and shadow. Some images show holes but they are regular, clean and clinical. Like the inside of her washing machine and round windows on the front of a building. It is precise. Contained. There are no cracks.

I ask if her course interacts with her trypophobia. “So far, not yet,” she says. “It’s a mix of theoretical and practical, and we’re taking photos of what we want to take photos of.”

I say her pictures look very linear. “I’ve never actually thought about it,” she says. “I love structure in the pictures. Maybe it’s about control.”

Have you had any treatment? I ask.

“Is there one?” she asks, surprised.

I stumble an answer about talking therapies.

Massanari tells me how some people with anxiety use things like pimple-popping, ASMR and miniature food (Google it – it is fascinating) to self-soothe.

“If you’re using these videos as a way of release and as a way of managing [anxiety] that can be both a really wonderful thing, but it’s also a really sad state of affairs,” says Massanari. “This is what people are doing because they may not have a lot of other outlets for professional support.”

For now, Julia will carry on as she has been, trying to avoid what she cannot stand. But even in sleep, she is not safe. Sometimes when dropping off, she sees pictures of holes which jolt her awake. Are they images you have seen before? I ask her. “No,” she says. “This is just my head making up holes.”

Once you know about trypophobia, whether you have it or not, you start to spot potential triggers everywhere. You start talking about it, too. In the pub, at work, in conversation with my mum, I am like Julia’s boyfriend or those Reddit posters, quickly pulling up a screen full of lotus seed pods, Surinam toads and honeycomb, reading the person’s facial responses. For many, it sounds too strange to be true. Just another socially contagious internet non-disease. Media coverage plays up populist angles – a Kardashian who goes “public with her trypophobia battle”, a celebrity chef who posts trypophobia-inducing images of beef wellingtons, or the student too scared of bubbles to do the washing-up.

What you don’t see – unless you go looking – is the debilitating power of one picture to ruin someone’s day or week. A compulsion to look at images that make you feel sick or panicky. Having to vet the movie you want to see with your child, the new boxset you have downloaded, the adverts on the bus, just in case something holey terrifying is waiting there.

Regardless of whether or not it is officially recognised as a phobia or another kind of condition, trypophobia is real for the people experiencing it. But as the internet plays its part in spreading these fearful images, it also facilitates connection. People from different continents who would never otherwise meet are online now discussing things like how upsetting a scene in the Wreck-It Ralph movie is.

In an online world that seems increasingly divided, subcultures like the ones based around trypophobia, ASMR and pimple-popping have one thing important in common. They remind us of our human-ness. Skin and bone. Flesh and blood. Whether with pleasure or digust, or a bit of both, we are feeling. We are alive.

• This is an edited version of an article first published by Wellcome on mosaicscience.com and republished here under a Creative Commons licence. Sign up to the Mosaic newsletter here.

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