Visuoperceptual processes in brain damaged patients on the digit symbol substitution test.

Alcoholic Korsakoff patients, patients with right hemisphere damage, and chronic alcoholics are impaired on the digit symbol substitution task (DSST) of the WAIS. To determine whether these deficits were related to psychomotor or visuoperceptive factors, several tasks and modifications of the DSST were administered to these three patient populations. While it was evident that psychomotor retardation contributed to the patients' poor performance, impairments in visuoperceptive processing were also found to be involved in the DSST performance of the three patient groups. It was concluded that while a psychomotor factor is the crucial variable in the performance of intact normal subjects, any of a number of visual processing variables (e.g., visual scanning, contour formation and organization) must be considered in assessing the deficits of brain damaged patients.