Ninety-five psychiatric inpatients (25 schizophrenic, 23 borderline, and 47 nonschizophrenic patients) were assessed on six indices of abstract and concrete thinking, during two stages of their disorder (acute phase and phase of partial recovery).
The level of abstract and concrete thinking in nonchronic patients was influenced by several factors. (1) During the prechronic phases diagnosis (schizophrenic vs nonschizophrenic) exerted some influence, but was not the most prominent factor. Evidence suggested, however, that during later chronic phases schizophrenic subjects may be extremely concrete. (2) Process schizophrenics tended to be less abstract than reactive schizophrenics. (3) The phase of the disorder exerted some influence (during active or acutely disturbed stages patients were less abstract). (4) The most powerful influence on the abstract-concrete dimension was intelligence. (5) Idiosyncratic thinking was an important negative influence on ability to abstract.
Harrow M, Adler D, Hanf E. Abstract and Concrete Thinking in Schizophrenia During the Prechronic Phases. Arch Gen Psychiatry. 1974;31(1):27-33. doi:10.1001/archpsyc.1974.01760130013002