What makes people more ticklish than others?
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When I was little, I had such a reputation among my family for being ticklish, my cousin would tease me by tickling the air above my body, sending me into a giggle fit. Years later, when I burst into laughter at a massage parlor, the masseuse told me she’d noticed that sensitive people are ticklish. I have been told that I’m rather sensitive, so I wondered, was there a correlation? And if not, what does make people ticklish?
Tickling is “tactile stimulation produced by someone that's not you,” says University of Maryland neuroscientist Robert Provine, author of Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond and Laughter: A Scientific Investigation. “It takes another person. If you could tickle yourself, you'd constantly be startling yourself.”
The laughter with which many people respond to tickling (whether they enjoy it or not) may be a reflex to dissipate tension, says Alan Fridlund, associate professor in the department of psychological and brain sciences at the University of California, Santa Barbara. “People automatically equate laughter with humor and play, but we also may laugh at funerals and at times of extreme tension and anxiety. The smile that occurs with laughter may be our way of adjusting our vocal tracts for the high-pitched giggles and shrieks we emit.”
Most people are at least somewhat ticklish, Provine tells me, and according to Fridlund, your level of ticklishness probably won’t change over time. There are two main theories as to why humans evolved to be ticklish. Psychiatrist Donald Black proposed that the tickle reflex motivates us to protect sensitive body parts. If this theory is right, then people with stronger reflexes (like when a doctor hits your knee and it jerks up) may be more ticklish.
The other theory about tickling’s origins is that we bond through it. “Tickle games are most likely part of infant socialization in every culture,” Fridlund explains. “The infant’s smiling and giggling reinforce the parents’ attention, and vice versa.”
Tickling may also be directly related to humor, Fridlund adds. “Charles Darwin and his contemporary Theodur Piderit both noticed the resemblances: We smile and laugh to both, and to get there, we need both an element of surprise and a light touch—physically for tickling, and verbally for humor.”
To see if this relationship between tickling and humor could be more than an analogy, Fridlund and his colleague Jennifer Loftis published a study of 100 college students in Biological PsychoIogy, which found that people who reported greater levels of ticklishness also reported a greater tendency to laugh and smile. They also found that ticklish people were more likely to blush, get goosebumps, and cry—all responses Darwin had considered part of hearty laughter. Fridlund and Loftis suggested that tickle games may not just be like jokes—they may start the developmental path that culminates in adult humor.
While there aren’t studies to back this up, Provine and Fridlund both believe that people who have some wariness about being touched are more ticklish to an extent. “My own hunch is that people who are un-anxious are less ticklish,” Fridlund says, whereas “highly anxious people may not let others near them except under strictly defined conditions and would be less likely to enjoy the surprise element in tickle games.”
Provine believes that the way our brains process social information could influence how ticklish we are. He once tested an autistic woman who felt nothing when the bottoms of her feet were tickled. “Given that tickle is associated with the neurological generation of ‘self’ and ‘other,’ it may be that individual differences in tickle may suggest a defect in the processing of this information that might exist in some autistic individuals,” he says.
One axis along which ticklishness does not differ much is gender, according to surveys Provine has conducted. “Men are more notably insisting that they aren't ticklish, but that generally is not true,” he says. “When put to the test, men are ticklish, too. I think by admitting you’re ticklish, this would suggest you would be under the control of someone else, and I think men would be less likely than women to admit that.”
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Regardless of how ticklish we are, our feelings about being tickled can vary. If you hate being tickled, this may be because your early experiences with it were negative. When people say they dislike tickling, Provine often finds that their siblings or other childhood adversaries used it to tease them, but they actually may enjoy it when they have control over it.
“As anyone who has ever been tickle-tortured knows, too much tickling can turn unfunny and become abusive, and the ticklee may be yelling ‘Stop! I mean it, stop!’ even though she continues smiling and laughing,” Fridlund says. “There's no fighting back by the ticklee because extreme tickling causes cataplexy, a temporary paralysis that occurs commonly with strong excitation.”
In adulthood, however, ticklishness can take on a more flirtatious meaning, with heterosexual people six times as likely to be tickled by someone of the opposite sex than the same sex, according to Provine’s research. “Tickle plays an important role in sex play,” he says. “It’s not so bad when, if they tickle you, you can reciprocate.”
So, I may never know if my ticklishness is related to my sensitivity. But I do know that my hatred for being tickled probably stems from my family’s relentless teasing. Who knows? If I can find a tickle partner who’s more respectful of my boundaries, maybe I could even come to enjoy it.
This article originally appeared on Tonic.