I am among the minority who figured out the "twist" in Sixth Sense well before it was revealed. Now, to be fair, I did go into it looking for clues - because I knew there was a surprise - but people had done a remarkable job of keeping silent about the nature if that surprise and I had not been given the slightest hint.
I believe I figured it out because I'm very attuned to color. I tend to link my memories to the color someone was wearing, or the color of a room. I noticed all those little bits of red Shyamalan placed at key moments.
Now, red does not inherently have a meaning that would associate it with the dead, but by using it consistently, the filmmaker imbued it with his own meaning. He does the same again in other films: red and yellow in The Village (where it was explained explicitly - and thus became too heavy-handed), in Unbreakable it was green and purple (which really gave me the sense of the comic-book world of the movie.)
Shyamalan uses it almost like a blog tag. Every time we see X we see color A.
I'm wishing I had sat down to re-watch Kurosawa's Ran before writing this blog. People comment all the time on how visually striking the color is, how it made the battle scenes so powerful, with the movements of the armies swirling against one another. But I would be interested to see whether the colors assigned to each son were purposeful. For instance, the faithful son was blue. (I have no idea whether there is a similar Japanese association as in the west - "true blue.")
Many directors use is to help set a mood.
American Beauty is an excellent example. Using the emotional associations we already have with red, the color is used to accent passion and sensuality. The red rose posy that is so tightly arranged is like Carolyn's restrained and controlled sexuality. Lester fantasizes about those red rose petals falling, coming loose, slipping wetly from a mouth...
David Lynch uses color in heightened ways to create his exaggerated moods and often a sense of uneasiness or surrealism...
But the director who comes to my mind most when I think of the intentional use of color as a storytelling element is Peter Greenaway.
Greenaway is a former painter, and his films show a strong visual sense, shots carefully framed. He exemplifies film as a visual storytelling medium better than any director I can think of - using the images themselves to convey meaning as much as any character or plot element. Nearly all of his movies use color in interesting ways. The film that most exemplifies this is probably The Cook, The Thief, His Wife, and Her Lover.
The Cook, The Thief is a rich and intense film of social and political criticism. (Among other things.) Each of the four characters represents a strata of society, and their relationships are how these strata interact with one another.
The Thief, who bullies them all, is consumerist capitalism - Thatcherist England. He's crass and abusive and greedy. His wife is society - kept tightly bound and dependent, mostly inured to the awful things he says and does to her. She seems icy, and yet yearns for something rich in all the ways her wealthy husband is not. The object of desire between two men. (But don't ever confuse one of Greenaway's women for a victim. They are vicious in their own way.) The cook is the working class and/or the artist - he's French, an immigrant, humiliated by his employer and yet he needs him in order to have a place to both earn his bread and practice his art... and the lover represents the intellectuals, carefully skirting consumerist society, trying to taste the good things without being destroyed by the greed. It's no accident that he reads about the French Revolution, and the chef whose art inspires him, who ultimately defies the Thief, is French.
(Greenaway himself likes to leave his work open to interpretation and comments little on meaning. The most he's said about this film is that it is about a "claustrophobic European situation" and that he compares to the baroque through visual cues. He wants to force the viewer to be an active participant in the art.)
Color is a major structural element, as much a part of creating the meaning as framing or editing.
The domains of these individuals are each color-coded. The ladies' room is white. All purity. The heavenly escape. The dining room is red and pruple, lurid and oppresively ostentatious (red: the "power color") - hell itself, where the devil reigns. The kitchen, which is the creative and fertile center of the film, is lush greens. The parking lot is in blues, not calm here but dark and otherworldly, almost menacing. This is a borderland between the restaurant and the ordinary world. The book depository (the lover's realm - away from the restaurant) in modest browns, leather and wood - things of true wealth and lasting value as opposed to the flashier and more temporal riches of the dining room.
There is also a brief use of yellow in the hospital, where it is used as a symbol of fertility and healing - as the yolk of an egg.
As the characters pass from one room, one realm to another - their clothing changes color to match. A dress that was red in the dining room is white in the bathroom. They are a product of their environments, changing easily. One exception is that the lover retains his brown clothing while in the restaurant - he is not effected by the lavish surroundings, does not belong to this realm - is only a visitor in hell.
Interestingly, the wife - who is the protagonist of the film, the one who undergoes a transformation in the ladies' room, is the only one who ever changes here. Though her lover meets her here, he is unaffected - and no one else enters. The room is so bright, it's almost a transformative fire.
The other character who retains his own color throughout, though he does not often leave his realm, is the cook (white, though his realm is green.) Despite his circumstances, the artist retains his identity. Perhaps he is already transformed.
I could go on a great deal longer about this movie - but the copy I ordered last week turns out to have been the wrong format, so I can't pop in the DVD and make notes and am relying mostly on my memory and a little research. (Couldn't recall what location was yellow, and whether the parking lot was blues or greys.)
But Greenaway's use of color makes clear that this element can be used not simply to make something pop on screen, or to make dramatic images - but to create meaning and structure in cinema.