When someone massages my neck or even just runs a finger across my skin it feels pleasant, but doing the same things to myself basically yields no sensation. I even remember going to the doctor as a child and enjoying the feeling of getting my ears checked with whatever the tool is they use for it, or the feeling when my grandma would comb through my hair to check for lice. Again doing it myself doesn’t feel nearly as good even though it’s the same physical movements. Why?
In: Biology
One theory that matches up well with experience and experimental data is that our brains constantly predict what’s happening with our bodies to minimize “surprisal” – basically, constantly trying to match up what it thinks with reality. In that process it can predict what your hand will do to your skin AND what your skin will feel when it happens. And because it knows what will happen, it’s already “priced into” the experience, and you don’t feel much. It’s like expecting to finish third in a race and then finishing third; it’s a blah experience. This is why we can’t tickle ourselves, either. The best book for more info is Surfing Uncertainty (edited to correct title).
Fun fact: there are mental illnesses where this predictive mechanism is faulty, so some people (I think schizophrenics?) can tickle themselves.
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