Does the sight of bubbles, crumpets and aerated chocolate freak you out?
New research hints at the cause of this unusual phobia that makes people panic at the sight of a cluster of holes.
Trypophobia is "the most common phobia you have never heard of," said study researcher Geoff Cole, a psychologist at the University of Essex, in England, who suffers from the fear himself.
The fear - which can cause symptoms like migraines, panic attacks, hot sweats and a racing heart - may steam from a visual resemblance to poisonous animals, Live Science reports.
The fear hasn't been investigated very deeply but a study by Cole and his colleagues found that 16 per cent of participants showed signs of trypophobia.
In his new study, one sufferer described the reaction to hole clusters: "[I] can't really face small, irregularly or asymmetrically placed holes, they make me like, throw up in my mouth, cry a little bit, and shake all over, deeply."
Even so, the phobia is not recognized as a disorder by the recently updated mental health manual, the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).
Cole's team wanted to know if trypophobic objects shared a common visual feature, so they compared 76 images of objects on a trypophobia website with 76 images of holes not associated with the phobia.
The images of trypophobic objects had high contrast at midrange "spatial frequencies" - repetitive spatial features of an image - compared with the nontrypophobic images.
They had the same visual structure as stripes, which can sometimes trigger migraines.
One trypophobic participant provided a clue to understanding the strong aversion to certain hole patterns: He reported having this same negative reaction to seeing a blue-ringed octopus, one of the world's most poisonous animals.
To investigate whether poisonous creatures could be causing the phobia, Cole and his colleagues analysed images of the blue-ringed octopus, the deathstalker scorpion, the king cobra snake and other poisonous snakes and spiders, finding that they all had high contrast at midrange frequencies, too.
Trypophobics' repulsive reaction to clusters of holes may be a side effect of an evolutionary adaptation to avoid poisonous animals, the researchers believe.
"We think that everyone has trypophobic tendencies even though they may not be aware of it," Cole said in a statement.
"We have an innate predisposition to be wary of things that can harm us."
Even people who don't fear such hole patterns rated the trypophobic images as less comfortable to look at, said Cole, who cured his own trypophobia by looking at the images so often he became desensitized.
To see how ingrained trypophobia might be, Cole's team is now studying how images of everyday objects, like watches, can be manipulated to make people prefer them more or less.
The study was detailed in the journal Psychological Science.
Read more: The ten most unusual phobias