The University of Sussex

Multiple personality and computational models

Margaret A. Boden

To be published in "Philosophy, Psychology, Psychiatry" (provisional title), the 1993-4 Royal Institute of Philosophy lectures. Multiple personality disorder (MPD) has reached "epidemic" proportions in the USA. It shows an extreme mental dissociation, with the same body presenting different cognitive-motivational streams of behaviour and experience at different times. It may be due to suggestibility and/or hypnosis, being an artefact (of therapy and media-publicity) rather than a genuine syndrome. Even so, we need to understand how it is possible for it to appear, and why it is that we are tempted to describe it in terms of "multiple personality". The latter question can be answered in terms of the cognitive-motivational integration criterian of "personality". If this is apparently split into two relatively distinct and internally coherent intentionalistic streams, the concept can still be applied -- but with more, and more fleeting, alternates this becomes increasingly indefensible. However, neither the clinical facts nor our normal concepts suggest multiple minds. Proponents of computational psychology need to explain its possibility (if not its aetiology) in computational terms. Various ideas within the computational literature are discussed which might be helpful for such a project.

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