Do you dream in color? If you answer Yes, how can you be sure? Before you recount your vivid memory of a dream featuring all the colors of the rainbow, consider that in the 1950s researchers found that most people reported dreaming in black and white. In the 1960s, when most movies were in color and more people had color television sets, the vast majority of reported dreams contained color. The most likely explanation for this, according to the philosopher Eric Schwitzgebel, is not that exposure to black-and-white media made people misremember their dreams. It is that we simply don't know...