The development of a cognitive model of schizophrenia: placing it in context.

This review provides a historical perspective on a model for schizophrenia based on results of experiments derived from learning theory. It was developed by the author in collaboration with Jeffrey Gray and numerous colleagues, (e.g. [Gray, J.A., McNaughton, N., 2000. The Neuropsychology of Anxiety. second ed. Oxford University Press, Oxford; Hemsley, D.R., 1987a An experimental psychological model for schizophrenia. In: Hafner, H., Gattaz, W.F., Janzarik, W. (Eds.), Search for the Causes of Schizophrenia, vol. 1. Springer, New York, pp. 179-188.; Hemsley, D.R., 1993. A simple (or simplistic?) cognitive model for schizophrenia. Behaviour Research and Therapy 31, 633-646]. It contrasts with earlier cognitive formulations [e.g. Hemsley, D.R., 1975. A two stage model of attention in schizophrenia research. British Journal of Social and Clinical Psychology 14, 81-88], which emphasised a weakening of contextually elicited response biases, and lacked a link to potential neural bases of the disorder. The model emphasizes the need to demonstrate patterns of performance that are not interpretable in terms of the well established 'generalized deficit' manifest in schizophrenia. It proposes that the cognitive disturbance is a change in the way stored material is integrated with sensory input and ongoing motor programmes. In particular, spatial and temporal context fail to activate appropriate stored regularities. A number of possible pathways from the cognitive disturbance to the symptoms of schizophrenia are outlined; again the term 'context' is widely employed. Thus, it has been invoked to explain the occurrence of hallucinations, delusions, thought disorder and disruptions in the sense of personal identity. However the term 'context' is ill-defined and the review indicates the variety of ways in which it may exert its influence. These are unlikely to reflect the operation of a unitary mechanism.