The inability to tickle oneself is a curious phenomenon that has puzzled many, including brilliant minds like Socrates, Aristotle and Charles Darwin.  Neuroscientist Konstantina Kilteni argues in a scientific article published this month in Science Advances that we should take tickle research more seriously.

 “Tickling is relatively under-researched,”’ says Kilteni, who runs a tickle lab at Radboud University in the Netherlands. ‘It is a complex interplay of motor, social, neurological, developmental and evolutionary aspects. If we know how tickling works at the brain level, it could provide a lot of insight into other topics in neuroscience. Tickling can strengthen the bond between parents and children, for instance, and we usually tickle our babies and children. But how does the brain process ticklish stimuli and what is the relationship with the development of the nervous system? By investigating this, you can learn more about brain development in children.”

The fact that you cannot tickle yourself is also interesting from a scientific point of view. “Apparently, our brain distinguishes ourselves from others, and because we know when and where we are going to tickle ourselves, the brain can switch off the tickling reflex in advance. But we don't know what exactly happens in our brain when we are tickled,” explains Kilteni, according to a press release from Radboud University.

One of the fundamental aspects of tickling is the element of surprise. When someone else tickles you, you cannot predict the exact timing, pressure, or location of their touch. This unpredictability catches your nervous system off guard, producing the ticklish sensation and often triggering laughter.

Gargalesis is a unique type of tickle, specifically the type that elicits a laughter response, and is often described as "heavy tickle". It's characterized by more intense tickling sensations, involving repeated touches or pressure on sensitive areas, often resulting in uncontrollable giggling and laughter. This type of tickle is typically experienced when someone else tickles you; it's usually not possible to tickle yourself in a way that produces gargalesis.

According to Study Finds, Kilteni says that the scientific understanding of gargalesis is “extremely poor.” She says we still don’t know why some areas of the body are more ticklish than others, and why some people enjoy being tickled while others dislike it. “The primary function of tickling in humans, as well as in other species, remains a big enigma,” she says.

Research also shows that people with autism spectrum disorder, for example, perceive touches as more ticklish than people without the disorder. Investigating this difference could provide insight into differences in the brains of people with autism spectrum disorder.

“But we also know that apes such as bonobos and gorillas respond to ticklish touches, and even rats have been observed being so. From an evolutionary perspective, what is the purpose of tickling? What do we get out of it?” Kilteni asks. Nobody knows why our armpits and soles of our feet are considered the most ticklish areas. They don’t have the thinnest skin or the highest concentration of nerve endings, says Study Finds. And from an evolutionary or survival aspect, scientists haven’t figured out why these two areas can cause the most tickling sensations.