Thriller Techniques

False Plateau
When the audience is lulled into a false sense of security as tension builds up as if something is going to happen and it doesn't, then something shocks the audience.


An example of this is in The Stepfather

When next door neighbour is looking for her cat in the cupboard us, the audience, immediately think its going to be the stepfather, this creates tension and a sense of security. When it is the cat that jumps out there is a relief in the audience. 

Then BAM the stepfather appears behind her surprising the audience and putting them into shock.

Bomb Theory

Alfred Hitchcock's Bomb Theory is a bit like dramatic irony. When the the audience know more than the characters in the film. This is meant to make the audience feel more engaged.