Tickling
Tickling results from a mild stimulation moving across the skin, and is associated with behaviors such as smiling, laughter, twitching, withdrawal and goose bumps.
Knismesis, also known as a "moving itch", is a mildly annoying sensation caused by a light movement on the skin, such as from a crawling insect.
Gargalesis reactions refer to a laughter-provoking feeling caused by a harsher, deeper pressure, stroked across the skin in various regions of the body.
[4] A German study also indicates that the gargalesis type of tickle triggers a defense mechanism for humans in the hypothalamus conveying submissiveness or fleeing from danger.
In 1939, Yngve Zotterman of the Karolinska Institute studied the knismesis type of tickle in cats, by measuring the action potentials generated in the nerve fibres while lightly stroking the skin with a piece of cotton wool.
[7] However, in some patients that have lost pain sensation due to spinal cord injury, some aspects of the tickle response do remain.
When circulation is severed in a limb, the response to touch and tickle are lost prior to the loss of pain sensation.
Laughter from being tickled [is manifestly a] reflex action; and likewise this is shown by the minute unstriped muscles, which serve to erect the separate hairs on the body".
[20] As with parents and siblings, tickling serves as a bonding mechanism between friends, and is classified by psychologists as part of the fifth and highest grade of social play which involves special intimacy or "cognitive interaction".
[21] It can also serve as an outlet for sexual energy during adolescence,[22] and a number of people have stated in a study that their private areas were ticklish.
Some of history's greatest thinkers have pondered the mysteries of the tickle response, including Plato, Francis Bacon, Galileo Galilei and Charles Darwin.
This titillation belongs entirely to us and not to the feather; if the live and sensitive body were removed it would remain no more than a mere word.Francis Bacon and Charles Darwin believed that humorous laughter requires a "light" frame of mind.
But they differed on ticklish laughter: Darwin thought that the same light state of mind was required, whereas Bacon disagreed.
Consistent with this idea, University of Iowa psychiatrist Donald W. Black observed that most ticklish spots are found in the same places as the protective reflexes.
[9] Most tickling is done by parents, siblings and friends and is often a type of rough-and-tumble play, during which time children often develop defensive and combat moves.
Although people generally make movements to get away from, and report disliking, being tickled, laughter encourages the tickler to continue.
[24] Gargalesis, on the other hand, produces an odd phenomenon: when a person touches "ticklish" parts on their own body no tickling sensation is experienced.
Heinz Heger, a man imprisoned in the Flossenbürg concentration camp during World War II, witnessed Nazi prison guards perform tickle torture on a fellow inmate.
Then he could not restrain himself and finally he broke out in a high-pitched laughter that very soon turned into a cry of pain, while the tears ran down his face, and his body twisted against his chains.
An article in the British Medical Journal describes a European method of tickle torture in which a goat was compelled to lick the victim's feet after they had been dipped in salt water.
Several reported tickling as a type of physical abuse they experienced, and based on these reports it was revealed that abusive tickling is capable of provoking extreme physiological reactions in the victim, such as vomiting, incontinence (losing control of bladder), and loss of consciousness due to inability to breathe.
