Cognitive skill
Working memory
The mental scratchpad that holds and updates information in real time.
Working memory is the mental workspace where you hold a small amount of information while doing something with it — a phone number while you dial, the last clause while parsing the next, the running total while shopping.
What it is
Working memory has a famously limited capacity — about 4 items for most adults — but the items can be chunks of arbitrary size. The clearest measurement task is the N-back: a stream of symbols arrives, and you flag when the current symbol matches the one shown N steps back. Hit rate minus false-alarm rate gives a clean signal that correlates with fluid intelligence across studies.
Why it matters
- Reading comprehension — you must hold the start of a sentence while parsing its end.
- Mental arithmetic — every carry, every partial product sits in working memory.
- Conversation — tracking who said what about which, especially in groups of three or more.
How it changes with age
Working memory capacity peaks in the mid-20s and declines gradually. Decline accelerates after 60, especially under load (distraction, time pressure). Sleep is the single biggest day-to-day modulator — a 4-hour sleep night shaves roughly 10–15% off capacity.
How to train it
Working memory trains slowly but persistently. The N-back drill is the canonical task — controlled studies show transfer to fluid-intelligence scores after 4–6 weeks of daily practice. Our 3-back drill in /train uses adaptive difficulty and tracks hit rate minus false-alarm rate so your scores are directly comparable across sessions.