Why can't people tickle themselves?

Answer 1

The tickling feeling is based on your brain not getting the signals it expected.

When you try to tickle yourself, you brain isn't surprised. It KNOWS exactly where (and how) your body is being touched.

However, you CAN tickle yourself by adding a factor outside of your own fingers. For example, you can tickle yourself by gently holding a stick and letting it wave around, almost randomly, across a ticklish area of your skin. Because your brain isn't able to predict the motion of the stick perfectly, you can feel a tickling feeling.

Answer 2

On some areas of the body you can tickle yourself, like the bottom of your own feet.

For the most part, I think you can't tickle yourself in other areas b/c you are using your own muscles, so therefore you are not as relaxed when you try to do it to yourself.

Answer 3

You can't tickle yourself because a tickle is a surprise response.
So if someone has a Dissociative Condition [Multiple Personalities], one of their selves can tickle another one of their selves all day long.