Level and variability of performance on neuropsychological tests.

Compared non-specific variability across subtests and overall level of performance on the Wechsler Adult Intelligence Scale (WAIS) and the Halstead-Reitan Battery (HRB) for normal, schizophrenic, acute and chronic brain-damaged Ss. Both variability and level of performance measures for each of the two test batteries significantly distinguished normal from abnormal Ss, but the HRB measures were more sensitive. Intra-S variability across subtests had a significant negative correlation with level of performance on the HRB, but not on the WAIS. This correlation could not be accounted for fully by a ceiling effect and was thought to represent in part a characteristic feature of ts performance on the HRB. While WAIS variability appeared to be independent of level of performance, it was not much help in differentiating between the four S groups. It was concluded that non-specific variability across subtests is not a helpful independent measure of neuropsychological function on the two batteries studied.