The classic working memory measure, in both directions — backward span is always the shorter one
Digit Span is the classic working-memory measure and a component of most standard IQ batteries. A sequence of digits is presented, then hidden, and you type it back — forwards, and in the harder mode, backwards. Backwards span is reliably shorter than forwards span, because reversing the sequence means manipulating it rather than just holding it.
A sequence of digits is shown one at a time.
Memorise it — nothing is displayed during recall.
Type the digits back in order (or in reverse, in backward mode).
Each success adds one digit to the next sequence.
The run ends on a mistake; your span is the longest correct length.
Choose forward or backward and a speed (each digit is shown for 1, 0.7 or 0.5 seconds with a short gap). Round one is three digits. After each correct answer the same sequence gets one more digit on the end, so you are always extending what you already hold.
One wrong answer ends the run. Your span is the length of the longest sequence you got right, and your best span is saved in this browser. XP is 10 per correct round.
Working memory span, split into holding (forward) and manipulating (backward). The gap between your two scores is informative in itself — a large gap suggests the rehearsal is fine and the manipulation is the bottleneck. Another memory game to try next: Pattern Copy.
Digit span is a subtest of the most widely used intelligence and memory batteries, in two forms. Forward span mostly measures how much you can hold; backward span also requires manipulating it, which makes it a purer test of working memory.
Backward span is reliably shorter — typically by one or two digits — and a 2004 study comparing age groups found that the forward and backward versions do not decline in the same way with age. Comparing your two scores is more informative than either one alone.
Chunk into groups of three or four the way you would a phone number. Chunking is the single biggest lever here.
Rehearse out loud or under your breath. Silent visual rehearsal decays faster.
Turn digit pairs into years, ages or prices — anything meaningful holds longer than a bare number.
For backward span, read the sequence into chunks as it arrives, then reverse chunk by chunk rather than digit by digit.
The frequently repeated 'seven plus or minus two' comes from George Miller's 1956 paper, which was about chunks rather than digits specifically. Real spans vary a lot with presentation speed, so track your own rather than comparing to a headline figure.
Forward span only asks you to hold the sequence. Backward asks you to hold it and operate on it at the same time, which competes for the same limited resource.
Practice reliably improves your score on this task. Whether that improvement extends to unrelated tasks is genuinely contested — the honest answer is that it mostly does not.
It is the same task. A clinical administration is standardised in ways a web version is not, so treat this as practice rather than as an assessment.