Why You Can’t Tickle Yourself: Scientists Tackle One of Life’s Weirdest Mysteries

NIJMEGEN, Netherlands — Ever try to tickle yourself? Go ahead, stroke your own armpit or foot sole right now. Feel absolutely nothing? That’s because your brain is playing a fascinating trick on you — one that has stumped scientists for centuries and exposes surprising gaps in our understanding of human behavior.

An extensive review published in Science Advances shows just how little we actually know about tickling, despite it being one of our most universal experiences. The research reveals that tickling remains largely understudied compared to pain, itch, and touch, even though brilliant minds like Socrates, Aristotle, and Charles Darwin all theorized about it.

“Gargalesis, commonly known as tickle, is a very familiar sensation that most of us have experienced at least once in life. Whether actively tickling our babies, family, friends, partners, or pets, or being on the receiving end of a tickle attack, humans undoubtedly engage in tickling behaviors,” writes study author Konstantina Kilteni, a neuroscientist from Radboud University and the Karolinska Institute in Sweden.

Yet “the scientific understanding of gargalesis is extremely poor,” she continues. “Today, we do not know why certain areas of the body are more ticklish than others and why some people enjoy being tickled, while others dislike it but still burst into laughter. We have also not fully understood why we cannot tickle ourselves and why some people are very ticklish, while others are not responsive at all. Furthermore, the primary function of tickling in humans, as well as in other species, remains a big enigma.”

So why is this seemingly trivial knowledge necessary? Understanding tickling isn’t just scientific curiosity — it could reveal new information about autism, schizophrenia, child development, and even help design better robots that interact with humans.

Scientists Can’t Even Agree on What Tickling Is

Part of the confusion stems from basic definitions. Researchers can’t agree on what “tickling” actually means, leading to wildly contradictory study results.

Some scientists study light, feathery sensations that make you want to scratch, like when a bug crawls on your arm. Others focus on the harder pokes and prods that make you laugh and squirm away. These create completely different responses, yet both get called “tickling.”

The light touch creates what researchers call “knismesis”—basically a moving itch that makes you pull away or scratch. But the laughing kind of tickle, which is what the term gargalesis refers to, requires fast, strong, repetitive pressure on specific areas like the armpit, sides, or foot soles.

Studies have produced opposite findings because researchers weren’t even studying the same phenomenon. Some found forearms and thighs most sensitive to tickling, while others identified these same areas as least sensitive. The paper notes these results “can be conciliated if we consider that the former studies studied knismesis and the latter studied gargalesis.”

Your Most Ticklish Spots Make No Scientific Sense

Nobody knows why certain body parts drive you crazy when touched. Your armpits and foot soles consistently rank as the most ticklish areas, but they’re not the most sensitive to regular touch or pain. They don’t have the thinnest skin or the highest concentration of nerve endings either.

One theory says these spots are vulnerable in combat — attacking someone’s armpit could damage major arteries, hitting the sides could harm internal organs. But this “warfare” explanation breaks down because our hands and arms are equally vulnerable yet not particularly ticklish.

Darwin proposed that we’re ticklish in places that don’t normally get touched by external sources. Our armpits rarely encounter random objects, so when they do get touched, our brains pay special attention. But even Darwin admitted this theory had problems; our backs and buttocks also receive limited external contact but aren’t especially ticklish.

After more than a century of research, scientists still have no solid explanation for why your feet make you giggle while your hands don’t.

The Brain’s Self-Tickle Suppression System

The strangest aspect of tickling is our complete inability to tickle ourselves. Scientists believe this happens because our brains predict and cancel out sensations we create ourselves. When you move your own hand to touch your body, your brain essentially says, “I know this is happening, so I’ll ignore it.”

Brain imaging studies support this theory, showing reduced activity in touch-processing areas when people touch themselves versus when someone else touches them. The cerebellum, which helps predict movement consequences, becomes more active during self-touch, apparently working to suppress the sensation.

But here’s the catch: all previous brain studies used non-ticklish touches or light stimulation. No one has actually scanned brains during proper tickling sessions, leaving this explanation somewhat speculative.

Do We Actually Enjoy Being Tickled?

Tickling triggers laughter, which usually signals happiness, but many people report mixed or negative feelings about being tickled. Some studies found only one-third of participants enjoyed the experience, while others disliked it but still laughed uncontrollably.

Research shows that tickling laughter sounds different from joy laughter: it has different acoustic properties, creates higher emotional arousal, and activates different brain networks. This points to tickling triggering a reflexive response rather than genuine amusement, similar to how cutting onions makes you cry without actually making you sad.

Not everyone responds to tickling equally either. Some people are extremely sensitive while others barely react at all. Children generally seem more ticklish than adults, though scientists aren’t sure if this reflects actual sensitivity differences or just behavioral changes.

People with autism spectrum disorder perceive touches as more ticklish than others, and individuals with schizophrenia-related traits show reduced ability to distinguish their own touches from external ones — they can essentially tickle themselves.

Current tickling research faces enormous practical challenges. How do you standardize a human tickler? Different people apply different pressures, speeds, and techniques, making results nearly impossible to replicate. Studies suffer from small sample sizes, inconsistent methods, and unclear definitions of what they’re actually measuring.

The researchers argue that future studies need automated tickling machines to deliver consistent stimulation while measuring multiple responses simultaneously— self-reports, laughter recordings, heart rate changes, and brain activity.

Despite two millennia of philosophical speculation and decades of scattered experiments, we’re still essentially clueless about one of humanity’s most common sensory experiences. Learning how our brains process and predict touch sensations could illuminate fundamental questions about consciousness, self-awareness, and sensory processing disorders.

The field also has practical applications in developing touch-based technology and devices that could revolutionize how we interact with machines and each other remotely. Most importantly, tickling opens a unique window into how our brains distinguish between self and other, a crucial ability that appears disrupted in certain mental health conditions.

Despite centuries of inquiry, Kilteni says that “we are only at the very beginning of this journey” to understand why a simple touch can transform into uncontrollable laughter — except when we do it to ourselves.