Each subject had their moment in front of the microphones and cameras. It has been established that anxiety and unfamiliarity suppress tickling. Each person was surprised by the tickling attack, but the team made sure each pair knew each other and felt comfortable. The tickler hid behind their partner as they watched a videoscreen that gave them randomized sequence of body parts to touch. Each spot got a quick tickle.
A person's facial expressions and breathing changed about 300 milliseconds. According to the write-up, the ticklee's cheeks raised, the corner of their lips pulled outward signals a joyful smile.
The vocalization happened at about 500 milliseconds. A normal vocal reaction time is less than a hundredth of a second. The team suspects that laughing requires more emotional processing.
They rated how ticklish each touch was. The crown of the head is not usually ticklish, so it serves as a control for what will happen when you tickle someone. Volunteers laughed audibly after about 70% of touches, and the louder they felt the tickle, the funnier they laughed. The sound of laughter was the most reliable measure of how intense each tickle had been.
Self-tickling was painless. The team noticed that self-tickling reduced the intensity of the other person's tickle. When self-tickling the same side, the occurrence of ticklee giggling fell by 25 percent. It was a shock to us. The data shows it very clearly.
Why would this happen? The question of why we can't tickle ourselves came up. According to the leading theory, tickling makes people laugh because of a brain error. It was confused by an unpredictable touch and went into a frenzy. No frenzy because self-touch is predictable.
It is not about prediction according to Brecht. He suggests that the brain sends out a body wide message when a person touches themselves. He says the brain has a trick to know if you touch yourself. He argues that we would all be tickling ourselves if it didn't.
Sophie Scott, a cognitive neuroscientist from University College London not involved in the work, says that it makes sense because our brains learn to turn down sensory perception when we are contributing to them. I feel a lot of sensations in my body when I sit. She says that it is less important to know if someone came in the room and touched her. The same effect occurs with hearing. The parts of your brain that are used to listening to other people are suppressed when you speak. She says that people are not good at judging how loud they are speaking. If the brain is preventing reactions to touch whiletickling, it would also be preventing reactions to being tickled.