Recently, I was asked about the use of “false action”, which was described to me as forcing characters to do something during dialogue because that’s better than having them just standing around. I had never heard of this exact terminology used to illustrate action, but I understood the concept behind it. However, not every concept is necessarily a good one, and this is never more evident than with writers guilty of applying this so-called “false action.” Big rookie mistake!
Starting with the word “false” is the first clue. When supporting points in an argument, for example, you don’t use false logic (or fallacies) to illustrate your claims, precisely because your audience will be skeptical of sweeping generalizations, jumping to conclusions, and non sequiturs, etc. Basically, because your presentation is based upon false thinking, you lose all credibility. And I would say that “false action” works the same way: it’s forced and unconvincing.
In fact, it would be very bad writing if false action was actually applied. The screenwriter's job is to find believable action for the character to do, something that is not only plausible, but probable. You have so little time in a screenplay to create believable and dynamic characters, and wasting it with "false action" is a sure fire way to lose your reader.
It’s true that characters should never be just standing around. Film is a visual medium after all, but if the dialogue doesn't require action, find a reason to have the character interact with his or her environment and use the character’s body to show another part of his or her personality.
While your hero is lambasting his baby brother for wreaking his car, for example, have him whipping up a culinary masterpiece. Or while your heroine is reciting some great legal exposition, have her organizing her desk like a consummate OCD patient. Whatever can show a glimpse into another part of their personality is what you’re after. Each moment is an opportunity to give more depth to your character; never waste it.