Symbol Digit Substitution Task

This test measures the speed of matching symbols to digits

The Digit Symbol Substitution Task is a well-established psychometric test paradigm which is used to measure general cognitive performance. Subjects must match symbols to digits and press the key which corresponds to the digit. The test is designed as a continuous performance task in which the subject must accomplish as many as possible correct matches within a three minute test period.

Since the task instruction is rather simple, yet demanding, the task is very popular to measure continuous performance with high mental workload. Since subjects learn over time the assignment while they perform the task, this test also includes a memory component. Due to this mix of involved cognitive functions, effects are rather unspecific, but reliable.


Lezak MD (1983). Neuropsychological Assessment, 2nd ed. New York: Oxford University Press

Lezak, M.D., Howieson, D.B., & Loring, D.W. (2004). Neuropsychological assessment. New York: Oxford University Press. pp. 368–370. ISBN 9780195111217.

Ryan, J.J., & Lopez, S.J. (2001). “Wechsler adult intelligence scale-III”. In W.I. Dorfman & M. Hersen. Understanding psychological assessment. Perspectives on individual differences. New York: Kluwer Academic/Plenum Publishers,. p. 23. ISBN 9780306462689

Wechsler, D. (1955). Manual for the Wechsler Adult Intelligence Scale. New York: Psychological Corporation.

Wechsler, D. (1981). Manual for the Wechsler Adult Intelligence Scale-Revised. New York: Psychological Corporation.


Configuration Options

Number of Symbols : 1 – 9
Key Mapping : 4-key (A,X,M,L) | 9-keys on numeric keypad
Symbold-Digit Mapping : Random | i-th variant
Mapping Table : Don’t show | Show before task | Show  during task
Task Duration : Duration of task in minutes