ABSTRACT
To the extent that the perception of illusory distortions constitutes a clearly definable aspect of normal perception, it would seem reasonable to expect that any theory of perception that claims that it can explain how form and extent are perceived should also be able to explain the perception of illusions. This chapter considers a number of contemporary theories of visual perception that claim to have some generality, in order to see how they treat the problem of visual illusions. A negative hypnotic hallucination essentially involves a procedure by which parts of the figure are hypnotically ablated so that the observer reports that he is no longer consciously aware of the stimulus. Critics of this procedure have asked whether the lack of response represents merely a change in verbal report or an actual change in the percept. It is clear that this question has important implications for the understanding of the nature of hypnosis.
