Thriller Techniques - Bomb Theory

Bomb Theory 

This theory was created by a man called Alfred Hitchcock; and this is the theory that the audience know more information than the characters in the film do and this makes us more engaged. For example, lets say there are a group of people on a boat floating around the sea and there is a shark coming towards them that only us can see creeping up next them while the people are still laughing a talking. This is a good example of the bomb theory. 
Another very good examples of the bomb theory is in this clip of 'The Stepfather'.

In this clip there are two examples of the bomb theory. In the first 2 minutes of the clip, the stepfather's shaving equipment is set out on the bathroom table. Seeing this, because of the beginning of the film, the audience knows that whenever they see his equipment he has already killed or is about to kill someone; and this works the audience up because at this point in time, the audience would be anxious and annoyed that she cannot sense the danger she is in.
Also in this clip, around 6-7mins into it, Michael is downstairs in the basement checking through the stepfather's things to get answers to the reasons why he has been acting so dodgy. After a while he was down there, the stepfather got out of bed, after checking if Michael's mum was sound asleep, and started to walk around the house. Seeing this, the audience works up anxiety, frustration, vexation, and distress and wish they could just tell Michael to "GET OUT OF THE BASEMENT!"