At a time when so many conversations seem to end up separating humanity into isolated pockets of contemptuous misery, it's heartening to know there's still something that we all share: the inability to physically tickle ourselves. But why is that, exactly? Why can someone else tickle us when we can’t even tickle ourselves? What is happening in our bodies that makes us react to tickling, and what is going on in our brains that helps us determine whether our reaction should be outrageous laughter or total repugnance? I decided to investigate.
Primarily, tickling begins in the most calculating organ in our bodies: the brain. Sophie Scott, professor of Cognitive Neurosciences at UCL, explains: "The main reason you can't tickle yourself is because your brain is very good at working out when sensations are caused by you. If you touch the back of your hand, you get less activation in the brain than if somebody else were to touch you. Tickling only works if there is someone else there."
The second key player involved in the act is trust. Yes, trust! "If tickling was aggressive, you wouldn't like it," asserts Professor Scott. "The idea of it being done with a safe and playful intention is what you've got to be able to trust in. We feel comfortable knowing that it's not going to become sexual or violent."
There are two types of tickling, one known as Gargalesis and the other as Knismesis. In 1897, psychologists Arthur Allin and G Stanley Hall identified Gargalesis as the type of tickling that can only be brought on by somebody else's touch, and which commonly results in laughter. Meanwhile, Knismesis is more of a heightened response to a delicate touch and not one that provokes feelings of amusement, meaning we're able to do this to ourselves. But what is it that makes us incapable of laughing when we touch ourselves?
Although our feet, belly and underarms are the places that are most commonly receptive to tickling, is it possible to experience tickling anywhere else? "It really depends on the anima," says Professor Scott. "If we're talking about rats, it appears that they are very ticklish on the nape of the neck. With humans, it's anywhere other than the face or the particularly nervy places – like your eyeballs, sex organs or the back of your throat – that are less receptive to the cordial touch. The effect of laughter mainly arises from the upper torso."
Beyond the mischievous rub and giggle, physiologically there can be bothersome consequences to a tickle – for example, the lack of breath we end up with after excessive laughter, or the even more inconvenient drama of tickling causing us to wet ourselves. The latter is actually a real condition, better known as "tickle incontinence".
"One of the things that happens when we laugh is that we start suppressing and turning off motor control," says Professor Scott. "We become floppy when we are laughing, and the reason we don't wet ourselves all of the time is because of motor control. You've got muscles in the bladder that are making sure you only urinate when it's the right time and the right place to do so. The phenomenon of tickle incontinence is quite common in childhood, and it seems to reflect the loss of motor control, particularly in the bladder when conjoined with laughter."
As for all the madman hard nuts who will brazenly claim to your face that they "just aren’t ticklish"? Well, there may be an amount of truth to the view that the human brain is strong-willed enough to resist any form of tickling. "There are a lot of other social factors that have to be in place to make it acceptable," says Professor Scott. "If I were to walk into one of my colleagues' offices and start tickling them, they would probably think I’ve taken leave of my senses.
"Our response to tickling is already quite modulated by context, so many people may find it's not acceptable based on that ground of thought."
For others, tickling may mean something other than laughter and could arouse feelings leaning towards a sexual nature. Take 34-year-old Barry from Wimbledon, who bravely explains that it can be an uncomfortable conversation explaining to new partners that he has a tickle fetish. Barry also divulges that he uses Craigslist to offer his tickling services in exchange for cash.
"I was around 20 years old when I first got into tickling," he recalls, misty-eyed. "Throughout my uni years I had an adventurous girlfriend who always wanted me to use toys on her. The day she asked me to caress her breasts with feathers was the day I became more intrigued by tickling. It was a mixture of watching her nipples become erect and her flirtatious laughter that was a real turn-on. It got to the point where I didn't even want to penetrate her anymore.
"Sadly, our relationship didn't last, but I haven't looked back since. It can be tough explaining my kink to new partners – many women think I'm a complete weirdo – but you'll always find others who are up for giving it a go."