It’s been awhile since I read it, but I seem to remember that Tolstoy’s novel Anna Karenina includes two strikingly different descriptions of journeys: an exuberant Levin going someplace just after Kitty has accepted his proposal of marriage, and a distraught Anna’s trip somewhere, perhaps to the train station where she killed herself. The details are hazy, but I remember clearly appreciating how well Tolstoy portrayed the world as seen, very differently, through the eyes of the ecstatic Levin and the despairing Anna.
Some recent research has examined the ways people’s view of the world changes, quite literally, depending on the mood they’re in. People who were primed with a happy-making image took a more expansive view of a second image, processing more of the details surrounding the image’s focal point, whereas those who were primed with a downer of an image focused more tightly on the central element of the second image and didn’t attend to the details in the background. This article from PhysOrg has more information, and points out that each level of attention—the broad and the narrow—has its uses, depending on circumstances.
The full citation is: Opposing Influences of Affective State Valence on Visual Cortical Encoding, by Taylor W. Schmitz, Eve De Rosa, and Adam K. Anderson. Journal of Neuroscience, June 3, 2009, 29(22):7199–7207.
As usual, the cool part is that this simply tells us about our nature, not about our identities. An individual can train herself to focus the same regardless of mood, and overcome this effect, or even to harness it.