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Being tickled isn’t always pleasant. Constant tickling can even lead to fatal fits of laughter – no wonder it was once used as a method of torture.
However, we cannot tickle ourselves. This is due to an innate reflex. For example, if we decide to touch our stomach with our left hand, this information is passed on to our brain and the sensation this may result in is calculated. If the brain’s prediction is correct in this case, we will feel nothing or very little.
In short: We require an element of surprise to respond to being tickled. However, our brain is always one step ahead of us, so we are unable to surprise ourselves. Experts have already conducted extensive research into whether it is possible to outsmart our brain.
Can we tickle ourselves if we think someone else is doing it?
Could a sufficient element of surprise be created by conjuring up the illusion that we are in another body and are tickling someone else – while in reality, we are tickling ourselves? Australian cognitive scientists George van Doorn, Jakob Hohwy and Mark Symmons tested this hypothesis. To accomplish this, the researchers used a complex apparatus designed to create the illusion of being in another person’s body.
The apparatus consisted of a wooden stick with soft foam triangles attached to both ends. The rod could be moved back and forth in a holder. A camera was mounted on a bicycle helmet and enabled the researchers to closely observe the participant’s right hand.
Participants were asked to place their hand on the surface where the foam triangles were located. During the experiment, their hand was moved using the apparatus either by the participant himself or by the experimenter, with the movement occurring synchronously or asynchronously with a visual representation of the participant’s hand. Nevertheless, the subjects did not register any tickling sensations. The researchers came to the conclusion that the participants were unable to create unexpecterd movement this way.
Remote-controlled self-tickling led to success
Sarah-Jayne Blakemore of the University of London then invented a tickling robot arm that moved the subjects’ limbs. Because the participants were tickled with their own limbs which were remote-controlled at the same time, enough of an element of surprise remained – and the test subjects felt the familiar sensation of being tickled.
