Studies of Thought Disorder in Schizophrenia: II. Plausible and Implausible Errors on a Modification of the Progressive Matrices Test

Introduction  The rationale of the present studies was presented in a previous paper.¹ Briefly, the argument may be recapitulated as follows: It is postulated that schizophrenia produces 2 kinds of mental change: (1) a reduction, variable in nature and degree, in level of intellectual function, and (2) qualitative changes in the nature of thought processes (loosening of associations, delusions, primary process thinking) which permit recognition of the illness as a distinct syndrome. Cameron² has designated these changes as "impairment" and "disorganization," respectively. It may also be suggested that they are analogous in some respects to the negative and positive symptoms described by Hughlings Jackson³ in neurological disease.Most psychometric investigations of cognitive performance in various clinical groups result in the findings that normal subjects achieve the highest mean scores, schizophrenics are intermediate, and subjects with chronic brain disease perform most poorly. It