Do you know why many people are ticklish? Scientists have unexpected explanations (video)

Scientists claim that the reaction to tickling can be both a way of protection and… a way of communication.

Among the many different forms of touch, only tickling causes people to burst into fits of laughter and involuntary movements. Scientists are still struggling to understand this phenomenon, the exact cause could not be determined unusual reaction. Sandra Proelss, PhD, at the Bernstein Center for Computational Neuroscience in Germany, notes that the human body's response to tickling is unique.

What is tickling?

The word “tickling” writes Popular Science, used in two meanings, which correspond to the terms knismesis and gargalesis, describing completely different reactions of the body to an external stimulus and different sensations.

The first is a light touch on the skin, like hair falling down your back, or the feeling of a feather on your arm. The technical term for this is knismesisThis may make you want to brush it off or scratch the affected area, but it's more of an itch than anything else and probably won't make you laugh.

There is also gargalesisa tickling sensation caused by repeated, strong pressure in a particularly sensitive area of ​​the body, which causes boisterous laughter. “These two things have to be considered completely separately,” explains Schimper Ishiyama, a neuroscientist at the Central Institute for Mental Health in Mannheim, Germany. The second phenomenon is much harder to explain, but scientists have several suggestions.

What is the reason for laughter during tickling?

According to neurobiologist Ishiyama, One hypothesis explains the tickling response as an attempt to protect a vulnerable part of the body. Scientists suggest that unexpected joy could potentially disarm an attacker and prevent potential harm. However, he is skeptical about this idea, since the most vulnerable parts of the body do not always correspond to those that are most vulnerable to tickling.

For example, most people find that tickling their feet causes them to burst into fits of uncontrollable laughter, and the back of their feet is not an area that needs special protection, says Ishiyama.

Scientists put forward a different hypothesis: laughter from tickling is a type of play and social connection. This hypothesis is confirmed by the fact that tickling is not only feared by humans, but also by anthropoid apes and… rats. What all creatures that react violently to tickling have in common is that they actively interact with representatives of their own species.

Sandra Proells notes that The strength of the reaction to touching sensitive areas depends on the emotional mood and the context that confirms this approach. Both humans and animals are more likely to respond positively and playfully to tickling when they are in a good mood and interacting with familiar people. But they are less likely to respond with laughter when tickled by someone they barely know, with a few exceptions associated with schizophrenia. Besides, says Sandra Proells, we can’t tickle ourselves – that response only exists in social settings.

Tickling and Brain Activity

A study of rats' brains showed that the same areas of the brain that are responsible for play behavior are activated during tickling. Also activated in response to this process are parts associated with processing touch, the fight-or-flight response, voice use, and emotional areas – the amygdala and anterior cingulate cortex.

Is tickling dangerous?

As we know, laughter is a sign of joy and pleasure. Although tickling can cause some discomfort, it is mostly associated with positive experiences. Research shows that People and rats alike seek out opportunities to re-experience the “attack” of laughter as a result of tickling. Scientists observed this behavior even when the participants tried to fight back in order to escape from the “offender.”

Proells argues that tickling may act as a reward system in rats during learning. Research has also shown that For some people, this process can cause so much pleasure that it becomes a sexual fetish.

Both humans and rats experience both fear of repeating an interaction and a desire to experience it again. Sandra Proells compares this mixture of emotions to those that arise before watching a horror movie or going on a tour of a haunted house. “The admixture of fear in pleasure makes the game more fun, because otherwise it is not exciting,” explains neuroscientist Shimper Ishiyama.

However Sometimes tickling causes a strong neurological and physical reaction, causes involuntary movements, changes the rhythm of breathing and can lead to stress. It is interesting that, judging by the results of an excursion into the depths of history, In the past, tickling was used as a form of torture. So outside the positive context of pleasant communication it can become a negative feelingespecially if the process gets out of control. Proelss says that in such cases, the victim's reaction will be more like suffering than laughter.

Even the fetishists interviewed in Shimper Ishiyama's study admitted that tickling felt like combination of pain and pleasure. Almost 40% of study participants responded that they experience pain when tickled.

Unanswered questions

What else do scientists not know about tickling? It remains an understudied phenomenon, as most neuroscience researchers focus on diseases and health disorders.

Sandra Proelss believes that there may be a genetic component to tickling, as some people are more susceptible to intense emotions during tickling. There is also a precise neurophysiological mechanism for tickling self-inhibition, the process of which is not yet fully understood. Scientists are not sure how many other animals experience human-like emotions through tickling, or how age affects the response.

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