Placing the audience in the position of Dramatic Irony does not eliminate all curiosity. The result of showing the audience what will happen is to cause them to ask, “How and why did these characters do what I already know they did? Dramatic Irony encourages the audience to look more deeply into the motivations and causal forces at work in the characters’ lives. This is why we often enjoy a fine film more, or at least differently, on second viewing. We not only flex the curiosity about facts and outcome, we now concentrate on inner lives, unconscious energies, and the subtle workings of society.
– Robert McKee, Story
Superior position is the [filmmaking] term for telling your reader or audience something that some of the characters in the story don’t know. This gives you one of your most powerful structural tools: anticipation. When we know who and where the killer is before the hero does, or when we know the hero is keeping a big secret, we will keep turning the page to see what happens when that conflict appears, or that secret is revealed.
— Michael Hauge
Hitchcock was a master of dramatic irony. He loved to hide from a character something known to the audience.