  Perhaps more sophisticated attempts to spell out the functions of consciousness are similarly doomed. But Allen &amp; Bekoff (1997, ch. 8) suggest that progress might be made by investigating the capacities of animals to adjust to their own perceptual errors. Not all adjustments to error provide grounds for suspecting that consciousness is involved, but in cases where an organism can adjust to a perceptual error while retaining the capacity to exploit the content of the erroneous perception, then there may be a robust sense in which the animal internally distinguishes its own appearance states from other judgments about the world. (Humans, for instance, have conscious visual experiences that they know are misleading — i.e., visual illusions — yet they can exploit the erroneous content of these experiences for various purposes, such as deceiving others or answering questions about how things appear to them.) Given that there are theoretical grounds for identifying conscious experiences with “appearance states”, attempts to discover whether animals have such capacities might be a good place to start looking for animal consciousness. It is important, however, to emphasize that such capacities are not themselves intended to be definitive or in any way criterial for consciousness.  Carruthers (2000) makes a similar suggestion about the function of consciousness, relating it to the general capacity for making an appearance-reality distinction; of course, he continues to maintain that this capacity depends upon having conceptual resources that are beyond the grasp of nonhuman animals.