Up: beat

Ingermanson says the following¹¹1 Randall Ingermanson and Peter Economy, Writing Fiction For Dummies (Hoboken, N.J.: Wiley Publishing, Inc., 2010).  (note that I am using term beat as a synonym for “motivation-reaction unit” even though there might be (subtle and not-so-subtle) differences):

Show first whatever happens fastest. Most often, this means that you show interior emotion first, followed by various instinctive actions or dialogue, followed by the more rational kinds of action, dialogue, and interior monologue.

Motivation (what Ingermanson and Economy call a “public clip”) consists of action, dialogue, or description.

Reaction (what Ingermanson and Economy call a “private clip”) consists of action, dialogue, interior emotion, monologue.

This originally comes from Swain.²²2 Dwight V. Swain, Techniques of the Selling Writer (University of Oklahoma Press, 1981). 

To do: contrast this to the story grid approach (inciting incident + turning point/progressive complications + crisis: motivation; climax + resolution: reaction).