Limitations in the use of intelligence test performance to detect mental disturbance

Abstract

"The Wechsler-Bellevue scale was administered to 40 morons and 80 schizophrenics, aged 30-39, and scores were compared with those of 210 controls of the same age range. Comparisons were made in terms of deviation scores expressing the performance of a patient on the individual tests relative to his own general level of performance." On the basis of the results, three diagnostic signs are tentatively suggested: (1) Adult morons display relatively low performance on arithmetic reasoning. (2) Adult schizophrenics perform relatively poorly on picture arrangement tests, and also (3) make a relatively poor showing on comprehension tests. Doubt is cast upon four other signs frequently found in the literature: (1) Relatively high vocabulary scores do not distinguish schizophrenics from morons. (2) Relatively poor scores on block designs test do not distinguish schizophrenics from morons or controls. (3) Variability from test to test does not distinguish morons from schizophrenics, although both are more variable than controls. (4) Superiority of verbal over performance scores does not characterize schizophrenics as a group, nor is the opposite distinctive of feebleminded. Extreme caution in labelling patients on the basis of test results is indicated. 24-item bibliography. (PsycInfo Database Record (c) 2025 APA, all rights reserved)