Tickling is a peculiar sensation that can cause uncontrollable laughter and a feeling of discomfort in the tickled person. However, have you ever wondered why it's nearly impossible to tickle yourself? This strange phenomenon is due to the way our brain processes sensory information and anticipates self-touch.

When we tickle ourselves, our brain anticipates the sensation that is about to occur. The cerebellum, a region in the brain that is responsible for coordinating movement, receives a copy of the motor command that is sent to the muscles when we intend to move. This copy of the motor command is used to predict the sensory consequences of our actions. When we try to tickle ourselves, the cerebellum predicts the sensation that our touch will produce, and the resulting sensation is reduced or completely eliminated.

On the other hand, when someone else tickles us, we are not in control of the tickling sensation. Our brain does not anticipate the sensation, and we are caught off guard. The sensation is then transmitted to the brain, and our response is one of discomfort and laughter.

Another factor that contributes to the inability to tickle oneself is that the sensation of tickling requires the element of surprise. The tickling sensation is most effective when it's unexpected, and the tickled person doesn't know when or where the next touch will occur. When we try to tickle ourselves, we are already aware of where and when we will touch ourselves, and our brain is not surprised.

To summarize, the inability to tickle oneself is due to the way our brain processes sensory information and anticipates self-touch. The cerebellum's prediction of the sensation, coupled with the lack of surprise, reduces or eliminates the tickling sensation.