ABSTRACT
Visual illusions are well known to students of perception. They are of interest because they are likely sources of information about veridical (accurate) perception. If we know the circumstances under which percepts are in error, then we should be better able to explain veridical perception. Illusions are, of course, sometimes studied simply because they are fascinating. Many attempts have been made to explain illusions, but research over the last hundred years suggests that it is unlikely that there is any one explanation for all visual illusions, or even all geometric illusions (those resulting from combinations of simple lines drawn on a page).
