When blocking is used well--especially in conjunction with good staging (and by staging I mean the placement of the camera)--it can make the difference between a series of events that are merely shown to the audience, or a powerful story that unfolds in an emotional and dramatic fashion.
I still remember exactly when I first realized this. Before I went to CalArts, I tried to see as many "classic" movies as possible to try and learn whatever I could about film making. I would always watch those films with an eye towards asking myself why the film makers made the particular choices that they made. Hitchcock's "Strangers on a Train" was one of the films I saw during that time, and there was one scene in particular that really turned on a light switch in my head when it came to how blocking could be used as a powerful tool in telling a story and creating drama.
In particular, what I learned while watching the scene was not just how blocking could help tell the story, but how the movements and postures of the characters could help illustrate the "gear shifts" of the scene: in this scene, as the conversation develops, the movements of the actors (as well as the placement of the camera) are used to separate the "phrases" of the conversation into sections to show us when one thought is ending and another is beginning, and to emphasize how the intensity and drama are ratcheting up as the scene proceeds. Through the whole scene, the blocking is used to support the underlying subtext of the script, which is exactly what blocking should do: illustrate the visual meaning of what is happening in the story.
If you haven't seen the film, it's definitely worth checking out. It's extremely well made and there's a lot to be learned from studying the way the film is put together.
I wish I had a clip of the scene that I could post, but I can't find one online anywhere. Instead, I will used some screengrabs that I found at the Hitchcock Wiki. But the techniques that I'm talking about are much more effectively illustrated by watching the film, so see it if you can. This scene takes place about 54 and a half minutes in, depending on which version you're watching (there are at least two different versions of the film that I know of).
In this scene, the Robert Walker character unexpectedly shows up at a party. There's tension in the scene because he's committed a murder with the knowledge of another character at the party (the Farley Granger character). Robert Walker plays a guy who is strange and unpredictable, and the Granger character is afraid that Walker's character will do something to embarrass him and possibly reveal the murderous pact that Walker has thrust Granger into. Also, Patricia Hitchcock is a guest at the party, and she happens to be wearing glasses that are similar to a pair worn by a woman Walker murdered earlier in the film. This will end up having an effect on Walker at the end of the scene.
If this sounds confusing, I apologize...I haven't seen the movie in years and I hope my description is accurate. Anyway, you don't really need to know all that to understand my points. If you want to read a better synopsis (with spoilers), here's the Wikipedia page for the film.
So as Walker mingles at the party, he introduces himself to a federal judge. He asks the judge how he is able to sleep at night, knowing he has sentenced convicted murderers to death.
The fact that he gets up and crosses to a seat sitting across from the two ladies is the precise moment where I realized how important blocking was when staging a scene, and that as a film maker, blocking is an important tool at your disposal. In real life, there's no earthly reason at all that you'd ever get up and move to a seat across from someone in the middle of the discussion. But it makes total sense here and really adds a lot to the scene and opens up possibilities for more dynamic shots as the scene unfolds. When watching the film, the movement of him changing places really gives a sense that things are starting to get more intense, and works perfectly with the dialogue, which is also getting deeper and more intense. His move separates this new, more intense "phrase" of the conversation from the previous "phrase" of the conversation, which was more casual. And you can see that by moving, he has created a more dynamic shot with more depth than the flat setup of the three of them sitting in a row.
Also, think about the fact that there are two ladies on the sofa, instead of just one. There's no reason for that that comes out of the story. As you'll see, the extra lady (the one on the left) never engages with Walker or has anything to do with the scene. So why not just put the one lady on the sofa?
If that were the case, then you'd be going from basically a two shot (Walker and the judge) to a two shot (Walker and the woman). The addition of a second woman on the sofa allows you to create some variety of shots so you can go from two shot to three shot and back to two shots again as Walker becomes more focused on the primary woman. Also, that progression really helps the scene build and give it a feeling of progression. To go from three shots to two shots to one shots (as the scene does as it goes on) gives a feeling of heightened drama and tension.
Now we can cut to this reverse shot below. Still a three shot, but it's dynamic and has depth. The ladies on either side of Walker gives him weight and makes him the solid center of the composition (this screengrab was missing on the Hitchcock Wiki so I re-used one from a later scene. Same composition though).
A reverse shot featuring the ladies on the couch. Obviously, you couldn't cut to a shot where the back of Walker's head bisected the middle of the frame and the two ladies were on either side of the frame. So this is a nice solution. Notice that it's still a three shot.
There's a disappointed reaction from her here that was not represented on the Hitchcock Wiki. I'll reuse this screengrab so you can get a sense of how it cuts.
So then Walker makes his pitch for how he would do it (and, as it happens, we've seen him murder someone this way already). He says the hands are the best tools...simple, silent and quick. He offers to show her what he means...
I hope my descriptions were clear and that you were able to grasp the overall idea of what I'm trying to say. Seeing the film is very helpful for getting a feel for what Hitchcock is doing and how the shifts of energy work and how they help dramatize the story. I really can't overstate how important blocking can be when you're trying to tell a narrative in a visual way. Audiences look for order and meaning in everything you put on the screen, and when blocking is haphazard--or fights the subtext of the story--it can be detrimental to the scene and the story.
In a future post I will talk about a couple of instances where I have been able to use blocking in order to help fix story problems in scenes that I storyboarded.