Digit Symbol: A Neuropsychological Test of Attention and Processing Speed

Digit Symbol is a neuropsychological test of attention and processing speed used to assess an individual’s cognitive functioning. It is a form of paper-pencil test commonly administered as part of cognitive tests such as the Wechsler Adult Intelligence Scale (WAIS) or the Wechsler Intelligence Scale for Children (WISC) (Wechsler, 1955, 1997). The test consists of a series of symbols displayed in a 5×5 grid. Each symbol is associated with a single digit ranging from 0 to 9. The test taker is asked to draw the digit associated with each symbol as quickly as possible. The time limit for the test is normally two minutes, and the number of correct responses is used as a measure of cognitive functioning.

Digit Symbol has been used as a measure of attention and processing speed since its introduction in the mid-1930s (Karnath, 1951). It has been employed in a wide variety of areas, including clinical assessment of cognitive functioning in dementia, traumatic brain injury, and schizophrenia (Kerr et al., 2018; Wertheimer & Lamberty, 1956; Ylvisaker et al., 1990). It has also been used to assess cognitive functioning in healthy individuals, such as in studies of age-related cognitive decline (Salthouse, 1991). Moreover, it has been used to assess the effects of pharmaceuticals, such as stimulants (Tilley et al., 2019) and anticholinergics (Skolnick et al., 2002), on cognitive functioning.

The reliability and validity of the Digit Symbol test have been extensively studied. It has been found to have good reliability, with a coefficient alpha of .77 (Salthouse, 1991). Studies have also found it to have good validity, with correlations between Digit Symbol and other measures of cognitive functioning ranging from .30 to .58 (Salthouse, 1991).

In conclusion, Digit Symbol is a widely used neuropsychological test of attention and processing speed which has shown to be both reliable and valid. It can be used to assess cognitive functioning in a wide range of individuals, including those with neurological and psychiatric conditions and healthy individuals.


Karnath, H. O. (1951). Digit Symbol Test. In H. O. Karnath (Ed.), Encyclopedia of Psychology (Vol. 4, pp. 488-490). New York: John Wiley & Sons.

Kerr, M., Bigler, E. D., & Tate, D. F. (2018). Neuropsychological assessment of traumatic brain injury in adults. Psychological Injury and Law, 11(1), 1-21.

Skolnick, B. E., Keefe, R. S. E., & Davis, S. M. (2002). Clinical utility of the Digit Symbol Substitution Test in schizophrenia. Schizophrenia Research, 57(1-2), 15-23.

Salthouse, T. A. (1991). Theoretical perspectives on cognitive aging. Hillsdale, NJ: Lawrence Erlbaum Associates.

Tilley, A. J., van Puijenbroek, E. P., & Burls, A. (2019). Short-term effects of stimulants on cognitive performance in healthy adults: A systematic review and meta-analysis. Human Psychopharmacology: Clinical and Experimental, 34(3), e2702.

Wechsler, D. (1955). The Wechsler Adult Intelligence Scale. New York: Psychological Corporation.

Wechsler, D. (1997). Wechsler Adult Intelligence Scale – III. San Antonio, TX: The Psychological Corporation.

Wertheimer, M. & Lamberty, G. (1956). The effect of Digit Symbol Test on schizophrenic patients. Journal of Abnormal and Social Psychology, 53(1), 47-51.

Ylvisaker, M., Turkstra, L., Coelho, C., & Szekeres, S. (1990). The Digit Symbol Subtest of the Wechsler Adult Intelligence Scale-Revised in traumatic brain injury: Relationships to demographic, cognitive, and functional variables. Brain Injury, 4(4), 307-313.

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