 Evans is not always clear whether he understands nonconceptual content to be a personal level or a subpersonal level phenomenon. And, in fact, it seems that Evans’s conception of nonconceptual content is in at least one important way deeply antithetical to that currently discussed. Whereas much contemporary discussion of nonconceptual content is focused on the content of conscious perceptual states, it looks very much as if Evans understands perceptual states with nonconceptual content as being non-conscious until the subject’s conceptual abilities are brought to bear on them (Campbell 2005). Nonetheless, the general idea that there might be ways of representing the world independent of the thinker’s conceptual capacities has inspired other philosophers. An early, personal level application of the notion is Tim Crane’s paper on the waterfall illusion (Crane 1988a. An illustration of the waterfall illusion, also known as the motion aftereffect illusion, can be found  here).  Crane argues that the waterfall illusion presents an experience with a contradictory content that hence cannot have a conceptual content—since conceptual contents must be consistent. This claim has provoked some debate (Mellor 1988, Crane 1988b).