When watching the film, I am especially impressed with the portrayal of John Nash by Russell Crowe. He managed to evoke emotion from the audience by the expression of his face, his eye contact with people around him, and his performance of a person that is plagued by schizophrenia is impeccable.
Schizophrenia isn't something that is easily shown, especially in medium such as films. He made his performance believable and convincing, because if you do have schizophrenia, you won't realize that you are sick. And that's what he did. He convinces himself that he's not sick, and that he is a spy working for the government in order to find information about Soviet Union's plans. He's frequently paranoid of someone following him, and even people around him sees that he frequently talked to himself, but dismissed it as a part of "peculiar genius" traits.
He eventually realizes that his delusions are not real. Not because of his 'government supervisor', not even his 'roommate', but because of Charles' niece, 'Marcee'. He realized that Marcee never grew old since he met her with Charles a few years ago, and he decided to seek help from Dr. Rosen.
Jennifer Connelly's performance in this film is impressive. She evokes powerful emotion as Alicia Nash, John's wife. Her facial expression when she realised that John relapsed and instantly thought about her son, which is in John's care. She hurriedly came home to see their infant son in the bathtub unsupervised because John thought that Charles was watching him.
Confused and tired with John's refusal to eat his medicine, and almost drowning their son to death, we can see in this particular scene that this is her breaking point, where she ran out of patience. It is not surprising that Jennifer Connelly won the award for Best Supporting Actress during the 74th Academy Awards due to this performance.