Hypnosis and conversion hysteria: a unifying model.

There are many similarities between the symptoms of conversion hysteria and phenomena produced in hypnotic contexts. This paper reviews some of those similarities and considers more general features associated with both hypnotic phenomena and conversion hysteria symptoms such as lack of concern, perceived involuntariness, the display of ''implicit knowledge'' and their apparently compliant nature. Neurophysiological and brain-imaging studies of hypnotically produced effects and conversion symptoms are described, which implicate frontal cortical structures in moderating the respective changes elsewhere in the brain, particularly in cingulate cortex. A recurrent theme is the apparent paradox which exists between, on the one hand, the subjective reality and involuntariness of both hypnotic phenomena and the symptoms of conversion hysteria and, on the other, the fact that objectively they appear to be role-congruent enactments responsive to the manipulation of motivational factors, expectancy, and social influence. A model of consciousness and self-awareness is presented which attempts to resolve that paradox whilst describing similar mechanisms underlying hypnotic phenomena and conversion hysteria symptoms. The model develops the idea of a central executive structure, similar to the notion of a supervisory attentional system, acting outside self-awareness but at a late stage of information processing which can be directly influenced from both internal and external sources to produce the relevant phenomena. The paper ends by proposing that as conversion disorder, pain disorder, and the dissociation disorders appear to be linked by a common mechanism they should be classified together under the heading of auto-suggestive disorder.