A German study has uncovered a hypothesis that could explain why we can’t tickle ourselves. The brain would be responsible in particular for this inhibition.
- Tickling triggers activity in the region of the brain that is linked to defensive behaviors. The burst of laughter caused by tickling would therefore be a protective reflex.
- In a majority of cases, surprise increases people’s sensitivity to tickling.
We know: certain areas of the body are extremely sensitive to tickling. This is particularly the case of the underside of the feet, the armpits or the trunk. This phenomenon is due to the density of tactile receptors in the skin on these parts of the body.
How do we react when someone tickles us?
In a study published in the journal Philosophical Transactions of the Royal Society B: Biological Sciences, researchers from Humboldt University in Berlin (Germany) evaluated the different responses to tickling in humans. Using their findings, they came up with a theory to explain why humans can’t tickle themselves.
For the purposes of the research, 12 volunteers were recruited. Participants were seated on chairs with bare armpits and feet. They faced a “tickling” partner who had to touch these two areas. Before the experiment began, volunteers and ticklers had time to get to know each other. GoPro cameras were also installed by the researchers to film the face and body of the participants.
According to the authors, the first reaction to tickling was a change in facial expression: a smile that was closely followed by an increase in the intensity of breathing. The tickled person then burst out laughing.
The brain would prevent us from tickling each other
The researchers also asked the subjects about the sensations they felt during tickling. According to their statements, their feet were more sensitive to tickling compared to their armpits.
The scientists then repeated the experiment, but asked the participants to tickle themselves. This time, the tickling had no effect on the volunteers. This observation allowed the researchers to develop a first theory on this phenomenon. When a person touches their skin, their brain would send signals inhibiting tickling, which would explain why we can’t tickle ourselves.
