working memory

Working memory is the limited mental system that holds a small amount of information for a short time while a person uses it.

It differs from plain short-term storage because it works on what it holds. Keeping a phone number in mind is storage. Adding two numbers in your head, or following a long sentence to its end, also means handling the information while it is held. The best-known account, from Baddeley and Hitch, divides it into parts: a central executive that directs attention, a phonological loop for speech and sound, a visuospatial sketchpad for images and locations, and an episodic buffer that links to long-term memory. Its capacity is small, a handful of items at once, though grouping items into larger familiar units lets each slot carry more.

Working memory matters because demanding mental tasks pass through it: reading comprehension, mental arithmetic, problem solving, following instructions and learning new words. When it is weak or overloaded, people lose track partway through a task, and low capacity is associated with difficulty at school. Stress and old age reduce it. Its limits explain why instructions are easier to follow in short steps and why new material is easier to learn in small, well-organised pieces.