Why It Is Nearly Impossible to Tickle Yourself

It turns out, it’s very hard to tickle yourself because your brain anticipates things going on around you in order to help speed up response times.  More technically, the cerebellum monitors body movements and can also distinguish between expected sensations and unexpected ones, generally resulting in diminishing or completely discarding expected sensations, while paying much more attention to unexpected ones.

Aha! The secret is out. Now, about that itch I can’t reach.