In the 1950's, dream researchers commonly thought that dreams were predominantly a black-and-white phenomenon, although both earlier and later treatments of dreaming presume or assert that dreams have color. The first half of the twentieth century saw the rise of black-and-white film media, and it is likely that the emergence of the view that dreams are black-and-white was connected with this change in media technology. If our opinions about basic features of our dreams can change with changes in technology, it seems to follow that our knowledge of the phenomenology of our own dreams is much less secure than we might at first have thought it to be