The stream of our consciousness contains an almost unceasing parade of sensation-like experiences, even in the absence of any external stimulation to produce them. We experience picture-like things, sound-like things, and more; our experiences can resemble any of our sense modalities. These experiences are what we refer to by the phrase "mental imagery." The images need not be vivid. People who doubt that they experience visual imagery are often persuaded by a simple exercise: count the windows