Editing Tickling (section)

==Self-tickling==
The question as to why a person could not tickle themselves was raised by the Greek philosopher [[Aristotle]].<ref name=Harris>{{cite journal|author=Harris, Christine R.|title=The mystery of ticklish laughter|journal=American Scientist|year=1999|volume=87|issue=4|page=344|doi=10.1511/1999.4.344|bibcode=1999AmSci..87..344H|s2cid=221586788 }}</ref>

[[Knismesis]] may represent a [[vestigial structure|vestige]] of the primitive grooming response, in effect; knismesis serves as a "non-self detector" and protects the subject against foreign objects. Perhaps due to the importance of knismesis in protection, this type of light touch is not dependent on the element of [[Surprise (emotion)|surprise]] and it is possible for one to induce self-knismesis, by light touching.<ref name=Selden/>

[[Gargalesis]], on the other hand, produces an odd phenomenon: when a person touches "ticklish" parts on their own body no tickling sensation is experienced. It is thought that the tickling requires a certain amount of surprise, and because tickling oneself produces no unexpected motion on the skin, the response is not activated.<ref name=Selden/> In 1998, Blakemore and colleagues analyzed the "self-tickle" response by using [[MRI]] technology to investigate how the [[brain]] distinguishes between sensations the person makes for themself, and sensations others create for. When subjects used a [[joystick]] to control a "tickling robot", they could not make themselves laugh. This suggests that when a person tries to tickle themselves, the [[cerebellum]] sends to the [[somatosensory cortex]] precise information on the position of the tickling target and therefore what sensation to expect. Apparently an unknown [[Cerebral cortex|cortical]] mechanism then decreases or inhibits the tickling sensation.<ref>{{cite journal |vauthors=Blakemore SJ, Wolpert DM, Frith CD |title=Central cancellation of self-produced tickle sensation |journal=Nat. Neurosci. |volume=1 |issue=7 |pages=635–640 |year=1998 |pmid=10196573 |doi=10.1038/2870|s2cid=9260106 }}</ref>

While the reasons for the inhibition of the tickling sensation during self-tickling remain unknown, research shows that the human brain is trained to know what sensation to expect when the body moves or performs an action.<ref>{{Scientific American Frontiers|11| 5}}</ref> Another reason may be the lack of awareness of many sensations arising from self-movement, such as not paying attention to one's own vocal cords. When one tries to tickle oneself by grabbing one's sides, the brain foresees this contact between body and hand and prepares itself for it. This removes the feeling of unease and panic, causing the body to not react to tickling in the same way it would if someone else supplied the stimulus.

However, some people with schizophrenia have the ability to tickle themselves. Non-pathological individuals high in schizotypical traits also have a greater self-tickling ability than people low in schizotypical traits. This is suggested to possibly correlate with a less pronounced ability of these people to track and attribute the results of their own actions.<ref>{{Cite news|url=https://digest.bps.org.uk/2016/03/22/people-with-schizophrenia-like-traits-can-tickle-themselves-whereas-most-people-cant/|title = People with schizophrenia-like traits can tickle themselves (Whereas most people can't)|newspaper = Research Digest|date = 22 March 2016}}</ref><ref>{{cite news |url=http://www.scientificamerican.com/article.cfm?id=tit-for-tat-delusions |date=21 December 2010 |last=Lametti |first=Daniel |title=Can't Tickle Yourself? That's a Good Thing |newspaper=[[Scientific American]] |access-date=8 February 2012}}</ref>