Dual N-Back · Guides
What is working memory? A plain-language explanation
Where the idea of working memory comes from, how researchers measure it, why its capacity is limited, and what an n-back task actually asks of it.
A workspace, not a warehouse
Working memory is the small amount of information you can hold and manipulate at the same time: a phone number you are about to dial, the first half of a sentence while you read the second, the running total while you add prices in a shop. It is distinct from long-term memory, which stores knowledge for years. The term was popularised by Alan Baddeley and Graham Hitch in 1974, who proposed a model with a central attention-control system and separate short-term stores for speech-like and visual-spatial information.
Why capacity feels so small
Research summarised by Nelson Cowan in 2010 suggests that adults reliably hold about three to five separate items in the focus of attention when they cannot rehearse or group them. People manage more in daily life by chunking: a familiar phone number is stored as a few groups rather than ten digits. The limit is on separate, unfamiliar pieces, not on the amount of meaning you can carry.
How it is measured
Common laboratory tasks include digit span, in which you repeat a growing list of numbers, complex span tasks that alternate remembering with a processing step, and n-back tasks, in which each new item must be compared with the one presented N steps earlier. Each task loads working memory differently; scores from one are not interchangeable with scores from another, and none of them is an intelligence test.
What a dual n-back task asks of it
Dual n-back keeps two streams in play at once, a position and a sound, and demands continuous updating: each turn you must add the newest item, drop the oldest and compare the current one with the item from N turns ago. This is why the task feels demanding at N=2 and above. Baddeley’s 2012 review notes that the exact architecture of working memory is still debated; what is not debated is that tasks of this kind rely on it heavily.
What this means for training
Practising an n-back task reliably improves performance on that task and on very similar ones. Whether it changes working memory in general, or reasoning, is an open question in the research literature, as the companion guide on training schedules explains. Dual N-Back shows your accuracy per session so that you can follow your own progress on the exercise without over-interpreting it.
Further reading
- Baddeley & Hitch (1974), Working Memory, Psychology of Learning and Motivation
- Baddeley (1992), Working Memory, Science
- Cowan (2010), The Magical Mystery Four: How is working memory capacity limited, and why?, Current Directions in Psychological Science
- Baddeley (2012), Working Memory: Theories, Models, and Controversies, Annual Review of Psychology