Ooh, very intriguing idea...
Situation: Imagine a world where color represented our thoughts.
What if there was a place where our emotions affected how we perceived color? For example, darker would (obviously) be a more "bad" thought, while lighter would be "good." And then, different colors themselves would signify different emotions as well. At birth, we take a mix of the color-emotions of our parents, but as experiences happen and we live our life, our interpretation of emotions changes colors, so to speak.
So, maybe to me extreme anger is represented as a light purple, while to you it's a deep crimson red? Misunderstandings would abound. Every thing you say may be seen in a different color by someone else, and if it has the same color, it may have a different meaning. Paintings would reveal much about how a person views the world, but only if you have a similar mindset as the artist already...thus creative expression would be limited.
Everyone's true interpretation of colors can gradually be reflected in their writing and actions, thus it is usually only extremely close friends who understand a person's viewpoint.
Also, stoplights would be impossible.

Andrew