How the scene components combine

The first components of a scene tend to focus on the external action. They typically involve “higher” energy and the events tend to develop the plot. Conflict is largely external. In general, the external action components move faster.

The remaining scene components tend to be more introspective and reflective. They typically involve “lower” energy because the main changes involve character development rather than external events that advance the plot. In general, internal reaction components tend to move slower.

The reaction portion of a scene is extremely flexible. The events therein might occur within a few seconds (consider an action hero, who must react to some disaster in an instant). Consequently the reaction might only require a few sentences, if any.

On the other hand, the reaction part of a scene might be entirely composed of twenty pages of inner monologue. Because this section is inward-facing, it’s a good place for backstory, flashbacks, and character growth.

Dwight Swain, who came up with these components, used different (and confusing) terminology to describe them. The “External Action” components he called a “scene” and the “Internal Reaction” he called a “sequel.” His intent was that the action is always followed by a sequel. Since these terms have other literary meanings, I prefer to avoid them.

The proportion of external action to internal reaction is a powerful tool to control the pacing of your story. 

In my opinion, using all six components in every scene is a little formulaic. Although there is a natural order to these components, you can occasionally drop one of the components or slice and dice the scenes to add variety to your plot.