Where Are People Most Ticklish? Researchers Map Ticklish Sensations Across Cultures

Ticklishness appears to be a distinct and specialized bodily sensation that people experience in remarkably similar ways across cultures, according to research by two neuroscientists. The study, published on 10 August in Nature Human Behaviour¹, provides a foundation for more standardized and systematic research into the science of tickling.

Humans are not the only animals that respond to tickling. Other great apes tickle one another, while rats and meerkats (Suricata suricatta) react to human tickling. These behaviours suggest that ticklishness may have been preserved through evolution. The form of tickling examined in the study is called gargalesis. It involves firm, repeated pressure that can cause laughter and involuntary movement and is often linked to social play. By contrast, knismesis is a very light, feather-like touch that does not usually produce laughter. Researchers have studied knismesis because it resembles itching, a symptom associated with several medical conditions, says Ziliang Xiong, a neuroscientist at Radboud University in Nijmegen, the Netherlands, and the study’s first author.

For many years, however, gargalesis received attention from only a small number of scientists. As a result, ticklishness remains “really a very poorly understood sensation,” says Michael Brecht, a neuroscientist at Humboldt University in Berlin who studies tickling in both rats and humans.

To investigate how people experience tickling, Xiong and his Radboud University colleague Konstantina Kilteni recruited 448 participants from three cultural groups: Dutch, Greek and Chinese. Participants first completed a survey about their experiences and attitudes towards tickling. They then used a computer to colour areas on a digital body model, creating maps that showed where they felt ticklish. The participants repeated the mapping task for other bodily sensations, including pain and pleasurable touch.

Nearly all participants, or 98.4%, said they had experienced tickling, while 95.8% said they had tickled another person. Reports of tickling were broadly similar across the Dutch, Greek and Chinese groups. Although this result may seem expected, previous research indicates that people’s interpretations of emotionally meaningful touch, such as hugging, can vary according to cultural background, says Kilteni.

The researchers also found that the body areas most sensitive to tickling were highly consistent across both individuals and cultures. Common ticklish areas included the neck, armpits, abdomen and soles of the feet. When the tickling maps were compared with maps for sensations such as pain and pleasure, the results indicated that ticklishness is a clearly separate experience. “Ticklishness seems to be its own class, physiologically and psychologically,” says Xiong. “It doesn’t seem that it is only a by-product or the integration of other body sensations.”