Some musicians and composers have a brain disorder that allows them to “see” music as colors or shapes. This sensory disorder is called synesthesia. Mozart is said to have had this condition. He said that the key of D major had a warm “orangey” sound to it, while B-flat minor was blackish. A major was a rainbow of colors to him. This may explain why he wrote some of his music using different colors for different music notes, and why much of his music is in major keys.
Schizophrenics are capable of tickling themselves because of their difficulties recognizing their own actions in advance. Tickling yourself is impossible in most people for the same reason that punching others seems half as forceful as it really is — your body offsets your own force. When you tickle yourself, your brain offsets that force and doesn’t respond the tickling.