Alfred Hitchcock once said that all art is emotion, and that the task of the filmmaker is to use the tools of his medium to manipulate the audience's emotional experience. In the scene above from the 1964 CBC documentary A Talk with Hitchcock, the great director demonstrates one of the most fundamental tools at a filmmaker's disposal: the Kuleshov effect.
In the early 20th century, Russian filmmaker and theorist Lev Kuleshov discovered that a single shot of an actor with an ambiguous expression on his face could convey a multitude of very distinct meanings in the mind of the viewer, depending on the nature of the shot immediately preceding it. In 1918 he conducted his famous experiment (below) using a single shot of the silent film actor Ivan Mozzhukhin's face looking at something off-camera. Kuleshov spliced it in with a series of quite different images--a bowl of soup, a dead child, a scantily clad woman--and discovered that the audience would interpret Mozzhukhin's emotion (hunger, pity, lust) depending on the juxtaposition.
Kuleshov's discovery was the outcome of a very deliberate process. In 1916 he and several colleagues made a systematic study of audience reactions at movie theaters across Moscow. They quickly found that the bourgeoisie were too reserved, so they spent most of their time at theaters in working class neighborhoods, where the emotions flowed freely. They noticed that audiences reacted differently depending upon where the film was produced. As Kuleshov writes in his essay, "The Principles of Montage":
When we began to compare the typically American, typically European, and typically Russian films, we noticed that they were distinctly different from one another in their construction. We noticed that in a particular sequence of a Russian film there were, say, ten to fifteen splices, ten to fifteen different set-ups. In the European film there might be twenty to thirty such set-ups (one must not forget that this description pertains to the year 1916), while in the American film there would be from eighty, sometimes upward to a hundred, separate shots. The American films took first place in eliciting reactions from the audience; European films took second; and the Russian films, third. We became particularly intrigued by this, but in the beginning we did not understand it.
Kuleshov eventually concluded that the essence of cinema is montage, that a film story is best told by cutting between discrete pieces of film. His student Sergei Eisenstein saw the basic structure as a collision between shot A ("thesis") and shot B ("antithesis") to create a completely new idea ("synthesis") in the mind of the viewer.
The notoriety of Kuleshov's experiment with Mozzhukhin tends to focus attention on the human face (it has even inspired scientific research on the contextual framing of emotional attributions), but the effect is far more general. "We are accustomed," writes Eisenstein in Film Sense, "to make, almost automatically, a definite and obvious deductive generalization when any separate objects are placed before us side by side."
Kuleshov showed this in several other experiments. In one, he depicted a single woman through a series of shots showing the body parts of multiple women. In another he created an "artificial landscape" by splicing an image of the White House into a sequence of images of Moscow. The willingness of audiences to make meaningful connections between unrelated images gives a filmmaker considerable expressive power. In his book On Directing Film, David Mamet writes:
Documentaries take basically unrelated footage and juxtapose it in order to give the viewer the idea the filmmaker wants to convey. They take footage of birds snapping a twig. They take footage of a fawn raising his head. The two shots have nothing to do with each other. They were shot days or years, and miles, apart. And the filmmaker juxtaposes the images to give the viewer the idea of great alertness. The shots have nothing to do with each other. They are not a record of what the protagonist did. They are not a record of how the deer reacted to the bird. They're basically uninflected images. But they give the viewer the idea of alertness to danger when they are juxtaposed. That's good filmmaking.
There is an old saying that a work of art is only completed in the mind of the beholder. Kuleshov showed that it's true.