What Is Working Memory? How It Works and Why It Matters

What is working memory?

A friend reads out a phone number, and before you can save it they ask you to work out your share of the bill. You repeat the digits under your breath, start on the sum, and somewhere along the way either the number or the total slips away.

That juggling is working memory, and the slip shows its most important feature: it holds very little, for a short time. Researchers use short-term memory for simply keeping information available, and working memory for keeping it available and doing something with it ^[1]. Remembering the phone number is the first; adding up the bill while you hold it is the second.

How it works: the multicomponent model

A classic model, proposed by Alan Baddeley and Graham Hitch in 1974, describes working memory as a system with three parts ^[2][3]:

• a central executive, which directs attention and decides what to work on;
• a store for speech and sound (now usually called the phonological loop): the inner voice that repeats the phone number;
• a store for images and locations (the visuospatial sketchpad): where things are, or what a route looks like.

In 2000, Baddeley proposed a fourth part, the episodic buffer, a limited store that binds information from the other parts and from long-term memory into a single episode ^[3].

This is a theory of how working memory is organised, and it is not the only one. Nelson Cowan, for example, linked the capacity limit to the focus of attention ^[4]. Models like these are background for understanding the exercises, not evidence that practising them changes anything.

How much can it hold?

In 1956, George Miller wrote about "the magical number seven": the span of immediate memory is about seven digits, and people stretch that bottleneck by recoding information into chunks ^[5]. Miller himself suspected the recurring seven might be a coincidence ^[5].

Later work suggests the real limit is smaller. Reviewing many kinds of data, Cowan argued that Miller's seven was a rough estimate, and that when people cannot rehearse or combine items into larger chunks, the limit averages about four chunks ^[4].

So why can most people repeat back more than four digits? In Cowan's account, rehearsal and long-term knowledge let them combine items into larger chunks ^[4], which is what you do when you split a phone number into groups. LaserMind's Digit Span has a Chunked mode that shows the same digits in groups of three, so you can compare it with the one-by-one version and see what grouping does for your own span.

How it differs from short-term memory

The two terms are often used loosely, and researchers disagree about how separate the two really are ^[1]. Repeating a door code back is a short-term memory task; adding up its digits while you hold it is a working-memory task. We look at the distinction, including where backward recall fits, in Working memory vs short-term memory.

Why it matters

You use working memory whenever you hold something in mind while doing something else: following directions, doing a sum in your head, keeping track of a conversation while planning your reply. In a 2002 review, Randall Engle noted that performance on measures of working-memory capacity predicts performance on a wide range of real-world cognitive tasks ^[6].

That is a correlation. It does not show that raising a working-memory score would improve those other tasks; that question needs training studies, covered below.

Working memory is also counted as one of the three core executive functions, alongside inhibition and cognitive flexibility ^[7]. See What are executive functions?

How working memory is measured

No single task measures working memory on its own. LaserMind has practice versions of three well-known research tasks.

Span tasks

A span task shows a sequence and asks you to reproduce it; the longest sequence you get right is your span. Simple span tasks, such as repeating digits in order, are usually treated as measures of short-term memory, while complex span tasks, which add a second job between items, are used to measure working memory ^[1].

On LaserMind's Digit Span, digits appear one at a time, about a second each, and you type them back with no time limit. The sequence starts at 3 digits. You get two tries at each length: if at least one is right, the next sequence is one digit longer; if both are wrong, the test ends. Your span is the longest length you got right at least once. Backward mode asks for the digits in reverse order. The digit span method page explains how to practise it.

N-back

In an n-back task you watch a stream of items and respond when the current one matches the one N steps earlier. An early version was described by Wayne Kirchner in 1958, in a study of short-term retention of rapidly changing information ^[8]. Because the item to compare against keeps moving, n-back asks you to update what you hold all the time, rather than store one fixed list.

On LaserMind's N-Back, a square lights up on a 3×3 grid every 3 seconds, and you press Match when it is in the same place as N steps back. N goes up after a block with at least 90% right and down after one with 70% or less. Your main number is the highest N you played with at least 80% correct. The N-back method page explains how to practise it.

The Corsi block task

The Corsi block-tapping task is the spatial partner of digit span: blocks light up in sequence and you tap the same path. A 2000 study standardised how it is given and scored, and described it as a test of visuospatial short-term memory ^[9].

On LaserMind's Light Path, nine blocks sit in a fixed, irregular layout and light up one at a time. The path starts at 2 blocks and can reach 9, with the same two-tries rule as Digit Span. Your main number is your spatial span, and there is a Backward mode here too.

All three are practice exercises, not diagnostic tests. Scores depend on your device, your attention on the day and how much you have practised, so LaserMind compares them only with your own history.

Can working memory be improved?

It depends on what "improved" means. Researchers separate three outcomes:

• the trained task: getting better at the exercise you practise;
• near transfer: getting better at similar, untrained working-memory tasks;
• far transfer: gains in different abilities, such as reasoning, reading, arithmetic or daily life.

In 2008, a widely publicised study reported that training on a demanding working-memory task (a dual version of n-back) transferred to measures of fluid intelligence, with larger gains after more training ^[10]. Later syntheses did not bear this out ^[11][12].

A 2013 meta-analysis of 23 studies (30 group comparisons), covering children and adults with and without clinical conditions, found that working-memory training produced reliable short-term gains on working-memory tasks ^[11]. For verbal working memory these gains were not sustained at follow-up; for visuospatial working memory, limited evidence suggested they might last ^[11]. There was no convincing evidence of transfer to verbal or nonverbal ability, inhibition, word decoding or arithmetic ^[11].

A 2019 review that brought together several meta-analyses of cognitive training found minimal effects on general cognitive skills, and found that differences between studies were explained by study quality and statistical artefacts ^[12]. A broad review of the brain-training evidence reached a similar conclusion: extensive evidence that training improves the trained tasks, less for closely related tasks, and little for distantly related tasks or everyday cognitive performance ^[13].

In practice, if you practise n-back or digit span, you will very likely get better at n-back or digit span. That gain is real and useful for tracking your practice, but it is not evidence that your everyday memory, your school or work results, or your intelligence have changed. Our review Science: brain games and IQ looks at the intelligence question in more detail.

What the research says

Frequently asked questions

Can I increase my working-memory capacity? Practice raises your score on the task you practise, and strategies such as chunking help you make better use of the capacity you have ^[5]. Meta-analyses have not found that training carries over to other abilities ^[11][12], and there is little evidence of effects on everyday cognitive performance ^[13].

I keep forgetting things. Should I worry? Everyone's working memory is small, and stress, lack of sleep, loneliness and lack of exercise can all impair the executive functions it belongs to ^[7]. If forgetfulness is new, getting worse, or affecting your work or daily life, talk to a doctor or another qualified professional: it can have medical causes, and online exercises cannot assess it.

References

1. Aben, B., Stapert, S., & Blokland, A. (2012). About the Distinction between Working Memory and Short-Term Memory. Frontiers in Psychology, 3, 301. https://doi.org/10.3389/fpsyg.2012.00301
2. Baddeley, A. D., & Hitch, G. (1974). Working memory. Psychology of Learning and Motivation, 8, 47–89. https://doi.org/10.1016/S0079-7421(08)60452-1
3. Baddeley, A. (2000). The episodic buffer: a new component of working memory? Trends in Cognitive Sciences, 4(11), 417–423. https://doi.org/10.1016/S1364-6613(00)01538-2
4. Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87–114. https://doi.org/10.1017/S0140525X01003922
5. Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81–97. https://doi.org/10.1037/h0043158
6. Engle, R. W. (2002). Working Memory Capacity as Executive Attention. Current Directions in Psychological Science, 11(1), 19–23. https://doi.org/10.1111/1467-8721.00160
7. Diamond, A. (2013). Executive functions. Annual Review of Psychology, 64(1), 135–168. https://doi.org/10.1146/annurev-psych-113011-143750
8. Kirchner, W. K. (1958). Age differences in short-term retention of rapidly changing information. Journal of Experimental Psychology, 55(4), 352–358. https://doi.org/10.1037/h0043688
9. Kessels, R. P. C., van Zandvoort, M. J. E., Postma, A., Kappelle, L. J., & de Haan, E. H. F. (2000). The Corsi Block-Tapping Task: Standardization and normative data. Applied Neuropsychology, 7(4), 252–258. https://doi.org/10.1207/S15324826AN0704_8
10. Jaeggi, S. M., Buschkuehl, M., Jonides, J., & Perrig, W. J. (2008). Improving fluid intelligence with training on working memory. PNAS, 105(19), 6829–6833. https://doi.org/10.1073/pnas.0801268105
11. Melby-Lervåg, M., & Hulme, C. (2013). Is working memory training effective? A meta-analytic review. Developmental Psychology, 49(2), 270–291. https://doi.org/10.1037/a0028228
12. Sala, G., & Gobet, F. (2019). Cognitive training does not enhance general cognition. Trends in Cognitive Sciences, 23(1), 9–20. https://doi.org/10.1016/j.tics.2018.10.004
13. Simons, D. J., Boot, W. R., Charness, N., Gathercole, S. E., Chabris, C. F., Hambrick, D. Z., & Stine-Morrow, E. A. L. (2016). Do "brain-training" programs work? Psychological Science in the Public Interest, 17(3), 103–186. https://doi.org/10.1177/1529100616661983