Why Can't I Tickle Myself?
When somebody tickles you and you squirm and scream, you’re responding more to the surprise than to the sensation, says Ellen Marmur, M.D., the vice chair of cosmetic and dermatologic surgery at Mount Sinai Medical Center, in New York City. Since our brains can predict our own movements, we’re less sensitive to them. But we’re very sensitive to unexpected touches, which is why we flail around when the Tickle Monster comes calling. Scientists believe the response might date back to our cave-dwelling ancestors, who needed to be on the alert for the skittering of bugs and rodents.