Why can't you tickle yourself?

Shot of a cheerful young man holding his son and ticking him while being seated on a couch at home.

For many of us, the tickling response is paradoxical — the playfulness it inspires is typically enjoyable, but the overstimulated nerves and loss of control can feel distressing. Whether you find it enjoyable, uncomfortable or somewhere in between, you can't tickle yourself. But why?

The answer has to do with the brain already knowing about and downplaying the expected, predictable sensation of the self-tickle, experts told Live Science.