Reaction shots are like the icing on the cake for a film scene. Their importance is as significant as the action the reaction is to. In this video tutorial, you will see why directors choose to incorporate such shots.
Filming dialogue coverage is one of the basics in filmmaking. That's not only to have variety of points of view to cut to, but to allow the viewer see how other actors react to a situation. Cutting into a reaction shot is like we, as a third person watching the scene, looking to the other side and seeing what the emotional outcome of what just happened is. Sometimes, it's the reaction shot that helps us understand what the other actor meant or did. There are cases when the reaction shot adds to the drama. Other times, it acts as a relief from the drama, introducing a bit of humor. Of course, reaction shots make it possible for the scene to last longer, so the viewer can have more time to go deeper into the situation and digest it. When thinking of providing coverage for a dialogue scene, don't just think of it as a diversity of perspectives. Think about the viewer who might be curious about the reactions of the other characters in the scene.
For more details on filming reverse shots and their importance to the scene check out the rest of the information on StudioBinder's blog.