Working memory, what it is and how it is measured

A definition

Working memory is the small space where you keep information while you do something with it. Holding a code while you type it, a phone number while you dial it, the start of a sentence while you read the end. It lasts seconds, holds little, and empties as soon as your attention moves.

It is related to short-term memory, which holds items, and differs from long-term memory, which stores what you learned days or years ago. Working memory is short-term memory put to work.

Seven, plus or minus two

Measuring how much a person can hold is one of the oldest exercises of psychology. In 1887 Joseph Jacobs measured how many digits his pupils could repeat, the first recorded digit span (Jacobs, 1887). In 1956 George Miller gathered results from many tasks that seemed to stop around seven items, give or take two (Miller, 1956).

The number is a rule of thumb rather than a constant. Grouping changes everything. Ten digits read as a phone number are three or four chunks, not ten items.

The classic tests

The digit span asks you to repeat a growing list of digits. In a computerized study of 763 adults, the average forward span was 6.52 digits (Woods et al., 2011). The number memory test is a visual version of it.

The Corsi block task asks you to repeat an order of positions. It has standard procedures and norms (Kessels et al., 2000), and computerized it reached a reliability of 0.85 in young adults (Morawietz et al., 2024). The sequence memory test is its digital cousin.

The chimp test comes from a study of numeral memory in chimpanzees (Inoue and Matsuzawa, 2007), and the online version asks you to recall numbers in order from their positions.

Age and working memory

Abilities do not all peak at the same age. In a study of 48,537 online participants, some abilities peaked around the end of high school, others plateaued in early adulthood and started to decline in the 30s, and others did not peak until the 40s or later (Hartshorne and Germine, 2015).

Practice also matters. Across 68 studies of working memory tests, scores rose between the first and second session and kept rising up to the fourth (Scharfen et al., 2018b). Part of a gain over a few days is the test becoming familiar.

The three Headgame memory tests

Sequence memory and the chimp test count in the Memory stat of the card, and on this site they are compared with their Human Benchmark norms (Human Benchmark, 2026). The number memory test is a season game, played freely until its own reliability is measured. Play the three, then compare how you do on order, on positions and on digits.

Sources

1. Woods D.L., Kishiyama M.M., Yund E.W. et al. (2011). Improving digit span assessment of short-term verbal memory. Journal of Clinical and Experimental Neuropsychology 33(1), 101 to 111. PMC2978794. doi.org/10.1080/13803395.2010.493149
2. Jacobs J. (1887). Experiments on prehension. Mind 12(45), 75 to 79. doi.org/10.1093/mind/os-12.45.75
3. Miller G.A. (1956). The magical number seven, plus or minus two. Psychological Review 63(2), 81 to 97. doi.org/10.1037/h0043158
4. Kessels R.P.C., van Zandvoort M.J.E., Postma A. et al. (2000). The Corsi Block-Tapping Task, standardization and normative data. Applied Neuropsychology 7(4), 252 to 258. doi.org/10.1207/s15324826an0704_8
5. Morawietz C. et al. (2024). Consistency of spatial ability performance in children, adolescents, and young adults. Frontiers in Psychology 15, 1365941. PMC10938598. doi.org/10.3389/fpsyg.2024.1365941
6. Inoue S., Matsuzawa T. (2007). Working memory of numerals in chimpanzees. Current Biology 17(23), R1004 to R1005. doi.org/10.1016/j.cub.2007.10.027
7. Hartshorne J.K., Germine L.T. (2015). When does cognitive functioning peak? Psychological Science 26(4), 433 to 443. doi.org/10.1177/0956797614567339
8. Scharfen J., Jansen K., Holling H. (2018). Retest effects in working memory capacity tests, a meta-analysis. Psychonomic Bulletin and Review 25, 2175 to 2199. doi.org/10.3758/s13423-018-1461-6
9. Human Benchmark, score distributions embedded in humanbenchmark.com, read on 13 October 2026. Reaction time n 70 940, sequence memory n 35 868, chimp test n 27 233, number memory n 24 084. humanbenchmark.com