Why Are We Only Ticklish In Certain Places? » Science ABC

There are different kinds of tickles

Our skin is able to detect different feelings. The skin uses different cells inside of it to tell us feelings such as touch, vibration and pain. Scientists think perhaps the feeling of being tickled comes when the skin cells are telling us we are feeling pain and touch together.

There are two types of feeling that are described as a “tickle”. Their scientific names are “knismesis” and “gargalesis”.

1) Knismesis occurs from a light touch, like a feather touching you and can happen on the skin anywhere on the body. This type is also seen in cats, dogs and lots of other mammals.

2) Gargalesis occurs from a heavier touch to “ticklish” parts of the body (like the tummy, underarms and the soles of the feet). This can make us laugh even if we don’t want to. This response also happens in apes.

               There are two main types of tickle.
There are two main types of tickle. , CC BY-SA

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Key Takeaways

  • The phenomenon of ticklishness has not yet been conclusively explained. Multiple theories to explain the phenomenon exist, and research is ongoing.
  • The social bonding theory suggests the tickle response developed to facilitate social bonding between parents and newborns. A similar theory posits that ticklishness is a self-defense instinct.
  • The reflex theory states that the tickle response is a reflex that is not affected by identity of the tickler.
  • There are two different types of "tickle" sensations: knismesis and gargalesis. 
  • Other animals experience the tickle response, too. Scientists have found that rats emit an inaudible vocalization akin to laughter when they are tickled.

The Social Side of Tickling

While that may explain the physical reaction that we have to tickling, the bizarre blend of pleasure and pain is still a bit of a mystery. Scientists have been fascinated by the social aspects of tickling for many years, primarily because tickling is one of the first physical interactions that mothers have with their children. Tickling a baby is a primal interaction within humans, as well as other primates and mammals, and helps to develop social, cognitive, and emotional bonds.

Mother Tickling Her Baby (Photo Credit: razyph / Fotolia)

This early method of communication carries over into childhood social interactions as well, and tickle fights are common between children, again helping to establish social interactivity and commonality. Furthermore, a relatively safe activity like a tickle battle helps children learn about sensitive, vulnerable parts of their body, imprinting an unconscious response to those areas, which may explain why we laugh or flex our muscles even when we are simply threatened with tickling, before any physical contact is made.

Tickling as a Reflex

Research into the physical response to tickling has led to conclusions that conflict with the social bonding hypothesis. The social bonding hypothesis really starts to fall apart when one considers those who find the experience of being tickled unpleasant. A study conducted by psychologists at the University of California in San Diego found that subjects can experience an equal degree of ticklishness regardless of whether they believe they are being tickled by a machine or a human. From these findings, the authors drew the conclusion that being ticklish is more likely a reflex than anything else.

If ticklishness is a reflex, why can’t we tickle ourselves? Even Aristotle asked himself this question. Neuroscientists at University College London used brain mapping to study the impossibility of self-tickling. They determined that the region of the brain responsible for coordinating movements, known as the cerebellum, can read your intentions and even predict exactly where on the body an attempt to self-tickle will occur. This mental process prevents out the intended “tickle” effect.

How To Tickle A Cat

According to Current Biology, cats will seek out tickles by initiating the physical interaction, which is done through head-butting or nuzzling you.

If the cat wants to leave at any time, allow this, or the cat may get overstimulated. This can lead to agitation or result in the cat escalating into playtime. While that sounds like a good thing, remember that cats often play with their teeth and claws.

If the tickling session is going well, you can get creative. Sometimes cats get bored if you continue the same motions. Once you start, change how you’re tickling after a while.

Keep the tickle sessions quick and with purpose. Tickling your cat too much or for too long can lead to them getting annoyed. These should be fun, short sessions that improve the human-feline bond.

What we think could be the cause

We can’t tickle ourselves. This is because your brain takes your movement and intention into account when responding to the sensation, and this reduces the ticklish nature of the touch. This could mean we use tickling to help us know what our own touch is.

Your brain has to deal with a lot of information coming in all the time. When that touch is from another person or thing, this is important to know – it could be a spider crawling on you! The knismesis feather-touch type of tickle might be part of our system for determining when something is touching us.

Some researchers think gargalesis, the heavy tickle, might help us learn to fight. The laughing from tickling encourages the tickler to keep going while the person being tickled tries to protect the ticklish parts of the body. It could be something like a reflex – just like when there’s a loud unexpected noise like a balloon popping in your face you can’t help being startled.

Why some people are ticklish and others are not, and why people have different ticklish spots is still a mystery!

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