Digit symbol substitution test

The DSST contained in the Wechsler Adult Intelligence Scale is called 'Digit Symbol' (WAIS-R), 'Digit-Symbol-Coding' (WAIS-III), or most recently, 'Coding' (WAIS-IV). Based on The Boston Process Approach to assessment, in order to examine the role of memory in Digit-Symbol-Coding performance, WAIS-III (but not WAIS-IV) contains an optional implicit learning test: after the Digit Symbol-Coding test paired and free recall of the symbols is assessed.

The National Health and Nutrition Examination Survey (NHANES) administered the DSST to over three thousand participants 60 years and older in 2011–2014. Trained interviewers administered the test at the end of a face-to-face private interview in an examination center and two interviewers independently scored the test. An extensive analysis of these data has been published. Scores (mean, 25th percentile, 75th percentile) declined with age: 60-69y: 57, 46, 68; 70-79y: 48, 38, 68; 80+y: 40, 29, 49.