Here’s why you can’t tickle yourself
Böhme and her colleagues conducted a series of three tests on different groups of experiment participants to learn about what’s going on in the nervous system and the brain during self touch and touch from others. In the first test, they placed subjects in an MRI and found that fewer areas of the brain were activated, and at a lower intensity, during self touch than when experimenters touched the subjects. In the third test, experimenters placed an electrode on subjects’ thumbs and used it to track how quickly the brain processes information from self touch and touch by others. They found that the perception of self touch was lower priority for the brains of their test subjects than the perception of touch by other people. This study demonstrated that test subjects’ brains clearly understood the difference between self-touch and touch by others, and weighted those two experiences differently.
Source: www.popsci.com