What the digit span test asks you to do
Digits appear on screen one at a time. When the run ends, a box appears and you type the digits back. The line above the box gives the direction: the same order you saw, or the reverse. Runs here are 3 to 10 digits long, and a session is three runs.
Scoring is by position. A digit earns a point when it is the right digit in the right place, so a run you almost get still counts for something. The same digit never appears twice in a row, so you never have to remember how many repeats went past. This version is visual, and there is no audio mode.
What it measures, and what it does not
It measures how much you can hold in mind for a few seconds and give back in order. Backward runs add a second job: reordering the run while you are still holding it. A backward run is the same length as a forward one, but it takes more work.
It does not measure long term memory, and it does not measure how well you learn. A span also moves a long way with technique, so it is a poor label for a person.
Where the numbers come from
The familiar figure comes from George Miller's 1956 paper. It reports a span of immediate memory that is about seven items long for a lot of different kinds of test material (Psychological Review, hosted by York University).
The paper also describes a way around the limit. Miller reports a demonstration by Sidney Smith, who grouped binary digits in pairs and in threes and gave each group a name. After drilling himself on this, Smith could repeat back far more binary digits than the plain span allows. Grouping leaves fewer things to hold.
Later work lowered the plain number. Nelson Cowan's 2001 review argues that the real limit averages about four chunks once grouping and rehearsal are blocked (Behavioral and Brain Sciences).
How to practice it here
Group the digits as they arrive, three and three rather than six in a row. Say each group once as it closes, then hold two groups instead of six digits. Read the direction line before every run, because the direction changes.
If backward runs keep breaking down, drop a level for a while. Every run gets shorter, forward ones included. Start with the digit span practice. The Read the recall direction lesson shows how forward and backward runs differ. For the grouping idea, see Remember patterns in groups.
Related practices on this site
- Running span. The run stops without warning, so grouping has to happen as you go.
- Sequence memory. The same idea with positions instead of digits.
- N-back test. Holding a short list while it keeps changing.
Questions people ask
What is a digit span test?
A digit span test shows a short run of digits and asks you to type them back, in the same order or in reverse. The longest run you can repeat is your span. It describes short term memory: how much you can hold for a few seconds and give back in order. It does not measure long term memory or how well you learn.
What is a typical digit span?
The familiar figure is about seven. George Miller's 1956 paper describes a span of immediate memory about seven items long for many kinds of material. Later work lowered the plain number. Nelson Cowan's 2001 review argues that the real limit averages about four chunks once grouping and rehearsal are blocked. Grouping and rehearsal are why the two figures differ.
Why is backward digit span harder?
A backward run adds a second job. You hold the run and reorder it at the same time. A backward run is the same length as a forward one, but it takes more work. On this site the line above the answer box says which direction to use, and the direction changes, so read it before every run.
How can you hold more digits at once?
Group them. Take the digits three and three as they arrive, say each group once as it closes, and hold two groups instead of six digits. Miller's 1956 paper describes Sidney Smith, who grouped binary digits and gave each group a name. After drilling, he could repeat back far more binary digits than the plain span allows.
How is the digit span practice scored here?
Scoring is by position. A digit earns a point when it is the right digit in the right place, so a run you almost get still counts for something. Runs are 3 to 10 digits long, and a session is three runs. The same digit never appears twice in a row. The digits are shown on screen, and there is no audio mode.