The person with schizophrenia is not a split personality.
Schizophrenia is the name given to a set of symptoms.
The symptoms are descriptions of different experiences. The person may say that he can hear people talking about him, commenting on what he is doing, being insulting or complimentary. He may hear these voices when he is alone. He may think they come from the television or radio or from invisible beings. He may say that he can pick up other people s thoughts, or that they can read his mind.