On Creating Suspense – Hitchcock discusses ‘Vertigo’ and ‘Psycho’:
‘One of the fatal things in all suspense is to have a mind that is confused. Otherwise the audience won’t emote. Clarify, clarify, clarify. Don’t let them say, “I don’t know which woman that is, who’s that?” ‘So,’ I said, ‘we are going to take the bull by the horns and put it all in a flashback, bang! Right then and there – show it’s one and the same woman … You can’t have blurred thinking in suspense.’
I remember seeing a film clip where Mr. Hitchcock talks about creating suspense. He spoke 1st of having two people have a conversation and then they go their separate ways. Boring. But say they are in a room with a bomb that’s set to go off in five minutes, and they don’t know that it’s there but the audience does, and they stand round having that conversation. That’s suspense. People will be talking back to the screen telling the actors to forget their conversation, and just get rid of the bomb under the table (or wherever it’s hidden) or else get out of the room before the bomb goes off. He also spoke of the McGuffin. That is the item that everyone is after in the course of the story, but which may or may not be what they think it is. The statue of the falcon in The Maltese Falcon is a good example. Everyone is out to get it and people are even killed over it, but in the end it turns out to be a fake. But of course the characters didn’t know that it was a fake while they were chasing after it.