Backwards Digit Span Test

About the Backwards Digit Span Test

The backwards digit span is the tougher sibling of the number memory test. A number flashes on screen — but instead of typing it back, you type it in reverse. See 372, type 273. Reversing digits means you cannot just echo the sound of the number in your head: you have to hold it AND manipulate it, which is the textbook definition of working memory. It is used in real clinical batteries (WAIS, WISC) for exactly that reason.

How to play

Press Start. A number appears for a few seconds.
Memorise it, then it disappears.
Type the digits in REVERSE order and submit.
Each correct answer adds a digit. One mistake ends the test.

What it measures

This test focuses on your working memory (storage plus manipulation). Most adults manage 4–6 digits backwards (versus about 7 forwards). Reaching 7+ backwards is excellent.

Why play it

Tests manipulation, not just storage — true working memory
Mirrors the backwards span task in professional IQ batteries
Typically 1–2 digits harder than forward span: a real challenge

Did you know?

Backwards span is a core subtest of the WAIS and WISC intelligence scales.
The average gap between forward and backward span is about 1–2 digits.
Visualising the number and reading it back off your mental image beats rehearsing the sound.
Backwards span correlates more strongly with reasoning ability than forward span does.

What counts as a good score?

Ranges below are drawn from published research — sources are listed at the end of the page.

Level	Digits recalled backwards	What it means
Developing	3 digits	Below typical adult backwards span, though very common on a first untrained attempt.
Average	4–5 digits	Typical adult performance, and the expected one-to-two-digit drop from forwards span.
Above average	6–7 digits	Strong executive control — you are manipulating the sequence rather than re-reading it.
Exceptional	8+ digits	Rare. Usually visual encoding: seeing the digits written out and reading the image right to left.

Backwards span runs consistently shorter than forwards span — typically by one to two digits — because reversal requires manipulating the sequence, not merely storing it. Both are standard WAIS subtests.

How to improve your backwards digits score

1.Picture the digits written down

Reading an image backwards is far easier than reversing a sound. This one switch is worth more than everything else combined.

2.Reverse in pairs

Split 4 7 2 9 into "47" and "29", flip the order to "29 47", then reverse within each. Two small operations beat one large one.

3.Start from the end immediately

Begin rehearsing backwards the moment the sequence finishes, rather than storing it forwards and reversing under time pressure.

4.Compare to your forwards score

The gap between your forwards and backwards spans is the interesting number — it isolates manipulation from storage.

Storage versus manipulation

Forwards digit span measures how much you can hold. Backwards span measures how much you can hold *while doing something to it* — and that difference is why the two appear as separate subtests in the Wechsler batteries. Reversal recruits the central executive, the control component of working memory, on top of the phonological loop that forwards span uses alone.

Because manipulation is the more cognitively demanding operation, backwards span is the more sensitive of the pair to fatigue, ageing and executive dysfunction. It is also the better predictor of performance on complex reasoning tasks, which is the practical reason clinicians bother collecting both.

Frequently Asked

What is a good backwards digit span?

Most adults manage 4–6 digits in reverse. Reaching 7 or more is excellent, and usually means you are visualising the number rather than rehearsing its sound.

Why is backwards span harder than forwards?

Forward span only requires holding information; backward span requires holding it while transforming it. That extra manipulation step is what makes it a purer measure of working memory.

What is the best strategy?

Picture the number written down, then read your mental image from right to left. People who switch from sound-rehearsal to visualisation typically gain a digit or two immediately.

Why is backwards span so much harder?

Because you are running two processes at once — holding the sequence and reversing it — and the reversal keeps interfering with the rehearsal keeping it alive. A drop of one to two digits from your forwards span is the normal, expected pattern.

What does the gap between forwards and backwards mean?

Roughly, how much of your working-memory capacity survives having to do something with the contents. A large gap suggests storage is fine but manipulation is the bottleneck. On a single casual attempt this is interesting rather than diagnostic.