The predisposition to hallucinate

It is argued that people who are predisposed to mistake a vivid imagination image for a genuine percept (i.e. hallucinators) should show an impaired ability to make clear perceptual-conceptual distinctions (i.e. boundary confusion) and should lack familiarity with internal sources of information. A test of these hypotheses was undertaken by comparing a group of "alcoholic" hallucinators with a group of "alcoholic" non-hallucinators. Some support is claimed for the "boundary confusion" hypothesis but not for the "lack of familiarity" hypothesis. Specifically, it was found that hallucinators performed significantly worse than non-hallucinators on the Embedded Figures Test (a measure of perceptual boundary confusion) and on the Intersensory Time Judgement Test (a measure of conceptual boundary confusion). These results are discussed in relation to other aspects of the predisposition to hallucinate. Some specific research needs are described.