Scientists are exploring the peculiar human experience of tickling—not through casual jokes, but through rigorous experiments. At Radboud University’s Touch and Tickle lab in the Netherlands, volunteers are being systematically tickled by a robot, while researchers monitor brain activity, heart rate, and physiological responses. This isn’t mere amusement; it’s a deep dive into why we are ticklish, what this tells us about pleasure and pain, and whether this odd behavior has a purpose. The answers could reshape our understanding of neural development, psychiatric conditions, and how we perceive reality.
Why Tickling Matters Beyond Laughter
The core question driving this research is deceptively simple: why do we laugh when someone (or a robot) unexpectedly prods our skin? The answer is not obvious. The sensation requires precise timing and intensity, as preliminary EEG scans show distinct brain activity during ticklish sensations. But beyond the physical response, tickling reveals something fundamental about how our brains process prediction and surprise.
Why is this important? Our brains constantly predict incoming sensory information. When those predictions are violated—like a sudden, unexpected touch—it triggers a unique response. This mechanism is disrupted in some psychiatric conditions, such as schizophrenia, where individuals may experience their own touches as more intensely ticklish, suggesting a breakdown in self-prediction.
The Social Evolution of Tickling
Tickling isn’t just a human quirk. Observations of bonobos at sanctuaries in France and the Democratic Republic of Congo show a strong correlation between tickling and social bonding. Older bonobos are more likely to initiate tickling, while younger ones are more often the recipients. This parallels human behavior, suggesting that tickling evolved as an infant-directed pro-social behavior that strengthens connections between individuals.
Tickling is linked to play-fighting. Actions that would be aggressive between strangers become pleasurable when shared between close relations, reinforcing bonds. Even unwanted tickling elicits laughter, implying a physiological reflex with deep evolutionary roots.
Beyond Great Apes: Tickling in Rodents
The puzzle deepens when we look beyond primates. Researchers at the University of Amsterdam have discovered that mice also enjoy being tickled, emitting ultrasonic laughter undetectable to humans. They even choose tickling over safe hiding spots, suggesting a genuine pleasurable response.
This raises a critical question: if rodents experience ticklishness, does it mean the behavior is more widespread than previously thought? Oostland hypothesizes that tickling evolved as a way for young animals to prepare for unpredictable environments. The surprise element of tickling may train brains to adapt to unexpected stimuli, improving survival chances.
The Unsolved Mystery
Despite progress, the ultimate purpose of tickling remains elusive. Theories range from social bonding and defense training to a fundamental neural reflex. The reality is that there are compelling arguments against all explanations. But one thing is certain: tickling is a bizarre, fascinating behavior that reveals core aspects of how our brains perceive the world, predict events, and connect with others.
Ultimately, whether tickling is a happy accident or an evolutionary adaptation, its study continues to shed light on the intricate workings of our minds and bodies.
