working memory

Meaning: Working memory is the active mental workspace that holds information briefly and manipulates it, as in mental arithmetic. In the Baddeley and Hitch model, the central executive directs attention and coordinates the parts; the phonological loop holds sound and speech-based information; the visuospatial sketchpad holds images and spatial layout; the episodic buffer combines these with long-term memory. Capacity is limited, about 7 ± 2 items (Miller), and unrehearsed content fades in roughly 20 to 30 seconds. Chunking groups items into meaningful units, so more can be held.

On the MCAT: Dual-task experiments are common. Two tasks that draw on the same component, such as repeating digits aloud while reading words, interfere more than a verbal task paired with a spatial one. In the serial position effect, the recency effect is usually attributed to items still held in working memory, and the primacy effect to rehearsal into long-term memory.

Common confusion: Working memory is not just a passive short-term store. Holding a phone number is storage; reversing its digits requires manipulation, which is the "working" part. The limit counts chunks, not raw items, which is why chunking helps.