There Are Two Types Of Tickling
You know the difference -- there's the type of tickling that causes a rush up your spine, and the aggressive laughing-till-it-hurts kind. Turns out, they actually have different names: knismesis and gargalesis, respectively. The two types of tickling were named by psychologists G. Stanley Hall and Arthur Allin in 1897. Knismesis is reminiscent of a feather trailing across your skin, or perhaps a bug walking on you. It's also the type of tickling that you can perform on yourself. Gargalesis, on the other hand, is more aggressive and can cause breathless laughter or even pain. It tends to target specific areas of the body where we are sensitive to tickling: underarms, waists, ribs, feet, and necks.
from The Royal Institution
Key Facts In This Video
Some believe that being ticklish evolved as a social mechanism to encourage bonding; others believe it serves as an alarm system. (0:38)
The cerebellum makes predictions about how sensations on your skin will feel when they're caused by your own movements. (1:13)
See a strategy for "curing" ticklishness: (2:13)