The digit span test initially was part of Wechsler’s Intelligence Scale, which was designed to measure a person’s intelligence quotient (IQ).
How the Test Is Administered
The digit span test consists of telling the person that you are going to give him a short test. The person is then told to listen carefully because you will say a series of numbers and ask him to repeat them back to you in the same order you say them.
The first series is three numbers, such as “3, 9, 2.” Each number is said in a monotone voice, one second apart. The person repeats those numbers back to you.
The next step is to speak a series of four numbers, such as, “4, 7, 3, 1.” Again, the individual repeats those back to you.
Continue in the same manner by increasing the series of numbers to five and ask the person to repeat the numbers back to you. Some test versions stop after a series of five numbers, while other versions continue increasing the series of numbers by one each time until the answers are incorrect.
Variations
This test can be varied by asking the person to repeat the numbers backward, that is, by starting with the last number you said and going backward to the first number you said. This is called the digit span test backward.
The digit span test can also be given visually by displaying a series of numbers and then asking the person taking the test to verbally state the numbers and then to write them down in the correct order. This is referred to as the visual digit span test and can be administered either forward or backward.
What the Test Measures
Administering the test forward and backward assesses short-term memory. When the backward version of the test is given, it also measures working memory.
Is the Digit Span Test Effective in Identifying Dementia?
In an article published in the International Journal of Alzheimer’s Disease, the digit span test demonstrated the ability to successfully identify someone with cognitive impairment and the researchers concluded this test should be part of a battery of tests used to detect mild cognitive impairment.
A second study conducted in Thailand found that the digit span test was effective in identifying mild cognitive impairment, while the verbal fluency test did not demonstrate that ability.
Detecting mild cognitive impairment is important for early detection and treatment of dementia.
Does the Digit Span Test Also Screen for Delirium?
While the digit span test can be used as a screening for dementia, other research suggests it may also be able to identify delirium (an acute change in mental ability that is often related to an infection or other illness). Additionally, one study found that it was also able to identify the combination of delirium and dementia, a condition called delirium superimposed on dementia. Delirium that develops while dementia is already present can be difficult to diagnose at times; thus, a test that has demonstrated the ability to detect this condition is useful.
Pros
This test is free, and it requires less than five minutes to administer. The test administrator does not require extensive training, and it appears to be effective in identifying cognitive problems in multiple cultures and languages.
Cons
The test is a screening tool, not a diagnostic tool, and it may be difficult to distinguish between delirium and dementia in patients where their history is not known.
Additionally, the results of the digit span test have been shown to be influenced by the amount of education someone has received, their age and their gender.
A Word From Verywell
The digit span test should be combined with other tests to develop an accurate picture of the person’s cognitive abilities. When used as a quick screening tool, it has shown to be effective in identifying potential cognitive concerns.
