callaway, why aren't people ticklish when they touch themselves the same way that others touch them and they are ticklish.
I looked this one up:
http://www.soundmedicine.iu.edu/archive/2001/mystery/tickle.htmlWhy can't you tickle yourself?If laughter really is the best medicine, wouldn't it be nice if you could tickle yourself into feeling better? But a touch to even the most sensitive feet, underarms and bellies can't evoke even a smile when the tickle comes from our own hands. Why do we convulse with laughter when someone else lays a finger on us, but are immune to our own touch?
For those of you who spent the break experimenting with today's medical mystery, you can blame your brain for cheating you out of a good laugh.
When someone else tickles us, our somatosensory cortex, the region in our brain that helps interpret external stimuli, signals the rest of the body to react. When we tickle ourselves, however, the somatosensory cortex gets signals from another region of the brain to remain inactive because the touch is coming from our own hands.
The culprit is the cerebellum, an area in the back of the brain responsible for controlling voluntary movement and predicting its consequences. Researchers have found that when subjects attempt to tickle themselves, the cerebellum forecasts what will result from the movement and signals the rest of the brain to ignore the resulting sensation. Some physicians use this knowledge when they examine extremely ticklish patients by having the patients put their own hands over the doctor's to trick the brain into expecting the touch.
Scientists have long believed that tickling evolved in early man as a defense mechanism to alert the body when foreign and potentially dangerous objects were touching it. That helps explain why we're ticklish in our most vulnerable spots, such as the belly, which covers many major organs, and the neck, which houses the vital jugular vein.
