There are many types of touch in the human vocabulary, such as stroking, pressing, tapping, and even pinching. But only one type of touch usually elicits laughter: tickling. From infancy to adulthood, just the movement of a few fingers on the stomach is enough to hear uncontrollable giggles and shrieks of laughter. But what is the cause of the reaction to tickling? Why tickle makes us laugh?
Sandra Prouels“Such a reaction is very specific,” says a PhD student at the Bernstein Center for Computational Neuroscience in Berlin. Tickle has unique features. In his research on neuroscience, Prouels has studied the human reaction to tickling. Although there are still great mysteries in this field, scientists like him have come up with interesting answers and explanations about why we are ticklish.
The first thing to note is that tickling involves two completely different sensations. The first type is feeling a soft and superficial touch like a hair falling on the body or a feather touching the skin. The scientific term for this type of tickling is “mild tickling” (knismesis) is known. The sensation may make you want to brush something off your skin or rub an area, but it’s more like an itch and probably won’t make you laugh.
The reason for the reaction to mild tickling is to reduce the possibility of bites and penetration of organisms into the body
On the contrary, the second type, which is called “intense tickling” (gargalesis) is known, has stronger pressure and more intense stimulation. This feeling occurs when repeated on sensitive areas of the body and usually leads to intense and uncontrollable laughter. Ishiyama shrimp“These two sensations are quite distinct,” says a neuroscientist at the Central Institute for Mental Health in Mannheim, Germany, who studies the neural mechanisms of tickling.
The reason for the mild tickling sensation is clear: to reduce the possibility of bites or penetration of unwanted organisms into the body. “This sensation occurs when you want to protect your body surface from parasites and insects, like a cow waving its tail to ward off flies,” says Ishiyama. “But explaining intense or deep tickling is a bit more complicated.”
What is the cause of tickling?
We still don’t know for sure why tickling exists, but a few theories have been put forward. According to Ishiyama, one theory says that such a reaction occurs to protect the sensitive parts of the body. A strong and happy reaction may deter the attacker from attacking. It is also possible that tickling protects the soft and vulnerable areas of our body. But he doubts the correctness of this theory, because the sensitive areas and the tickling areas of our body are not exactly the same. For example, the soles of most people’s feet are sensitive to tickling, but this area does not need much protection. “There are many exceptions, but I don’t think this theory is definitive,” Ishiyama says.
The theory Ishiyama favors is that being tickled is a form of play and social communication, and may also be useful as training for fighting. Man is not the only tickling creature in the world; Other social mammals such as great apes and some rodents (especially gerbils) show a similar response to tickling. What all tickling creatures have in common is that they are highly social mammals, playing, being violent, and communicating with each other.
There are other points to support game theory and social bonding. Prouels says the degree of tickling depends on the emotion and the meaning behind that sensation. People and animals are more ticklish when they are in a positive and playful mood. “Reactions also vary based on familiarity, if a stranger tickles people, they usually don’t laugh,” he adds. Anxiety can also reduce the sensation of being tickled. Also, except in exceptional cases such as schizophrenia, we cannot tickle ourselves; This reaction is only seen in social situations.
Finally, neuroscientists traced some brain regions involved in the sensation of tickling. Through a study of mice, scientists found that the same physical sensory circuits that are involved in play behavior are also lit up during tickling. Other areas of the brain that are activated by tickling include areas responsible for processing touch, the fight-flight response area and sounds, as well as emotion processing areas in the brain, such as the amygdala and cingulate cortex.
Is tickling always enjoyable?
Laughter is a sign of joy and pleasure, and tickling, although there is an aspect of discomfort in it, is primarily considered a pleasurable activity. According to experiments and experimental observations, both humans and rats seek opportunities to be tickled, even if at the moment of contact, they are apparently struggling to escape the “claws of the tickle monster.” While training house mice, tickling can be used as a reward system, says Proels. In some humans, tickling can be too pleasurable.
The existence of fear in the heart of pleasure makes the game more exciting
Interestingly, both humans and mice, when they know they are going to be tickled, show dual signals that even include fear. But this does not prevent the experience of tickling again. Ishiyama explains that the combination of sensations from a single tickle is similar to the thrills experienced by someone who eagerly seeks out experiences such as visiting haunted houses or watching horror movies. “Having a little bit of fear in the middle of the fun makes the game more exciting, because without it, the game wouldn’t be as exciting,” he says.
Of course, any experience becomes annoying if it exceeds the limit. Tickling also causes strong reactions on the nervous and physical level. It causes involuntary movements and reactions, changes the rhythm of breathing, activates different areas of the brain, often causes the person to gasp, and can quickly become a stressful experience.
Also, historical evidence confirms that in the past, tickling was used as torture, because outside of the positive context of play and familiarity, it can become a deeply unpleasant sensation, especially when it is out of control. In such situations, Prouels says, the victim’s reaction is more like fear and distress than it is funny.
Even participants in Ishiyama’s experiments have noted that tickling is a combination of pain and pleasure. Almost 40% of the participants stated that they also felt discomfort and distress during consensual tickling.
What do we still not know about tickling?
Despite all the research done and scientists investigating this issue, tickling still remains a relatively unknown phenomenon. “I’m a fan of positive emotion research,” says Ishiyama. “My ultimate goal is to understand the brain mechanisms involved in pleasure and entertainment.” But most neuroscience research focuses on diseases and disorders. Perhaps for this reason, there are still many unknowns about tickling.
For example, some people are very ticklish, while a few are not ticklish at all. Genetic factors seem to play a role, but “that’s one of the biggest mysteries,” Proueles said. “Also, the neural mechanism that prevents us from tickling ourselves has not yet been fully identified, although we are working towards the answer.”
Also, Ishiyama says, we don’t know how many other species of animals experience the same sensation. He has recently started his research on mice. The issue of the relationship between ticklishness and age is still raised; This sensation seems to decrease with age and the cause is still unknown. In addition, the evolutionary path that led to the existence of tickling in several species also needs research.
Finally, the researchers say that they have obtained information based on the investigations carried out, but to fully understand this complex phenomenon and the riddles of tickling, more research on smiling mice, chimpanzees and humans is needed. How ticklish are you?
