Difference between touching yourself and someone else touching you?

I was washing my hair a while ago and it struck me that massaging your own head feels nothing like someone else massaging your head. This is also true for scratching your back and touching yourself on the sexual bits. Why the big difference?

According to a recent study

It may be ‘well known’ that you can’t tickle yourself, but it’s false. Or at least not universally true.

Certainly, part of the difference is completely tactile. When someone else shampoos your head, your brain is receiving only the sensation of your head being touched. When you shampoo your own head, your brain is processing simultaneously both the sensation from your head AND the sensations from your fingertips. Feeling both cannot be the same as feeling only one. You can approximate the sensation of only being touched (and not touching) by wearing thick gloves.

There’s also the feedback element; when you touch your own body, you automatically adjust the pressure, area of contact, etc to that which is comfortable to you; when someone else touches you - or vice versa - there is no such feedback, so the pressure may be softer or harder to that which you are most familiar, and this adds to the alienness of the sensation.

I always thought it was because when you try to tickle yourself, your brain tells your hand to move in a certain direction, but the same brain is also putting that new portion of your skin on notice that it’s about to be touched. The element of surprise is gone. When someone else touches you, you’re not aware of what’s about to be touched, so your brain can’t prepare those nerve endings.

When I anticipate the tickling I have incredible resistance against it. It’s really only the initial, caught-offguard to tickling that sucks. Once you accept it as happening, it’s essentially just like trying to tickle myself – just doesn’t work.