A sequence of digits appears, one at a time. Type it back from memory. Each round it grows longer — how far can you hold the line?
Digits flash up one after another. When they stop, type the whole sequence back in order. Get it right and the next one grows by a digit.
Digit span is one of the oldest and most robust measures in neuropsychology. The number of items you can hold and reproduce reflects the raw capacity of your verbal working memory — the buffer you use for everything from a phone number to a line of argument.
Within a programme, span tasks are paired with EEG so we can see not just how much you hold, but how efficiently your brain does it — the difference between straining and gliding.