Brain training: memorise a growing sequence of digits, then type them back. Forward, backward, or mixed.
Digit span is the oldest and most widely used measure of short-term memory capacity.
Forward span is phonological loop storage. Backward span adds the manipulation component - you must reverse the sequence in mind.
Normal forward span is 7±2 (Miller's law). Backward span is typically 1-2 digits shorter.
The game stops after two consecutive failures at a given length.
Digit span is a subtest of the Wechsler intelligence scales and correlates with overall cognitive function.
Chunking - grouping digits into meaningful pairs or triplets - reliably increases span. Professional mnemonists have demonstrated 70+ digit recall using elaborate systems.
The raw capacity of your verbal short-term store, measured in digits.
Forward digit span isolates passive verbal short-term storage: how many ordered items the phonological loop can hold and reproduce before they decay. Your span is the longest sequence you reliably recall in correct order. It reflects storage capacity and rehearsal speed more than reasoning, attention switching, or long-term knowledge.
Backward span, by contrast, forces you to hold and reorder the sequence, recruiting executive working memory rather than pure storage, so it usually runs one to two digits shorter. Everyday correlates are concrete: holding a phone number or verbal directions just long enough to act before you write them down.
Push your span by one digit at a time and rehearse aloud in rhythm.
Start at a length you clear easily, then add a digit only after two or three clean recalls. Subvocalise the sequence in a steady cadence as it appears, and chunk it into groups of two or three, the way phone numbers are spoken. Train forward first; add backward trials once forward span feels stable.
The common failure is grabbing for the whole string at once, which lets the early digits fade before you reach the end. Anchor the first two digits firmly, since primacy items are the ones people most often drop under length. Avoid silent staring; without active rehearsal the loop empties in a couple of seconds.
Read your span as a personal trend, not a fixed number.
Forward span clusters around seven for adults, with most people landing between five and nine; backward span typically sits a digit or two lower. A strong result is consistently recalling longer forward sequences and keeping backward span close behind. Watch your own moving average across sessions rather than fixating on a single best run.
Span is highly state-dependent: fatigue, noise, stress, and even quiet background speech shrink it, so an off day says little about your ceiling. A high span also does not predict reasoning, problem-solving, or memory for meaningful material, which rely on different systems. It measures verbal holding capacity, nothing more.