 is a difficult and controversial issue, but it is clear that whatever they are, they are certainly not anything much like the things we actually see. (They seem to deserve the label 'image' largely because they involve some of the same neural machinery that is used when we really do observe; but we don't have eyes inside our heads.) Several psychologists have argued that there are in fact no such things as mental images, and certainly every workable model of them involves something much more like a proposi