Digit symbol substitution test (DSST) is a neuropsychological test sensitive to brain damage, dementia, age and depression. The test is not sensitive to the location of brain-damage (except for damage comprising part of the visual field). It consists of (e.g. nine) digit-symbol pairs (e.g. 1/-,2/┴ … 7/Λ,8/X,9/=) followed by a list of digits. Under each digit the subject should write down the corresponding symbol as fast as possible. The number of correct symbols within the allowed time (e.g. 90 or 120 sec) is measured.
A user is shown a key that maps numbers to abstract symbols. This key is visible at all times during the task. They are given a brief initial practice session where they are presented with each of the nine symbols in numerical order along with number pairing in an apparently random order and asked to identify the corresponding number. Then they are given nine symbols in an apparently random order and asked to identify the corresponding number. If the user is able to achieve 75+% accuracy in the practice session, they move on to the full task. Otherwise, they repeat the practice up to four times. If after four attempts they cannot achieve greater than 75% accuracy, the task is discontinued.