 Apparitional experiences would seem to lend support to the importance of central factors, since they represent a form of quasi-perceptual experience in which the role of external stimuli is minimal or possibly non-existent, while the experience nevertheless continues to be phenomenologically indistinguishable from normal perception, at least in some cases.The interest of apparitional experiences to psychology has acquired an added dimension in recent years with the development of the concept of schizotypy or psychosis-proneness.This is conceived of as a dimension of personality, continuously distributed throughout the normal population, and analogous to the dimensions of extraversion or neuroticism.