Measuring people with fMRI scientists have shown that brain activity is suppressed when we touch ourselves as opposed to being touched by others.
This suppression starts as early as the spinal cord before it even gets to the brain.
It seems the brain knows that self touch is less likely to have either a pleasurable or a painful result, and therefore considers it expected and less important. As babies we learn where we end and the world starts by other peoples touch.
Even more interesting is that researchers have shown that the brain also suppresses it’s activity from the skin being touched by an unrelated object (a piece of wood in this study) if at the same time, the person touched their own arm compared to if another person touched their arm.
In other words, less sensation is felt by the person if they touch their arm at the same time.
This could be why we intuitively rub a body part when it gets hurt. Neurologically doing this will actually most likely help you feel less pain.
That’s pretty cool to know.