The interest curve
Increasing interest is called building. If we had to rely on natural interest, providing an effective interest curve would be a hopeless task. Fortunately, we can call a whole battery of technical devices to our aid.
We build interest by adding more: more movement, more color, more sound, more light, more people, more intensity, more concentration, more excitement. In short, anything whatever that the spectators regard as interesting will also increase their interest.
A stage act gives you plenty of scope. You can start with a bare stage and fill it with production items, or start with black-and-white costumes and apparatus and end with a riot of color. Begin with minor effects like a cigarette vanish and wind up by producing an automobile. Commence with small slow movements and end by racing around the stage waving silken banners. Open silently and close with a shout and a pistol shot. If you have adequate lighting facilities and a reliable electrician, nothing is more effective than starting with a fairly dim stage and ending in a blaze of light.
My own pet device for building interest consists in increasing the height of my actors above the stage floor. This works so well that I often introduce steps and platforms merely to make height possible…
One of the dramatist’s most important jobs is to relieve the audience of all mental effort. Each step should be clear, and the transition from one step to the next should seem easy and natural. When a step does not logically follow the one before it, the spectators are puzzled. While they are groping for the connection, they miss the next step—or the next few steps. This confuses them still more. Confusion makes the interest curve drop sharply; people who are trying to understand what has happened cannot give full attention to what is happening.