Hypnosis
If the doctor actually reaches Robert when Prot is hypnotized, and Robert can speak and move, why can't Robert speak or move after Prot leaves his body?
shareHypnosis taps into the part of the brain that when we are awake we have no control of, essentially this space is for storing memories and other information.
When Mark hypnotizes Prot, Prot speaks of his friend, who he will not name. That friend is Robert and Robert never spoke to Mark rather Prot spoke to Mark about what Robert was experiencing. When he was woken up Robert returned to the subcinscious of Prot because Robert was so traumatized about his wife and daughters death that he created a second person so he did not have to remember the experience. Mark could not talk to Robert because Robert had basically ceased to exist.
I think the above seems line a good explanation.
Its that man again!!