Working Memory and Its Role in IQ
Working memory is the cognitive system that holds and manipulates information over short timescales — the few seconds during which you mentally hold a phone number while you walk to the keypad, or the moment you keep three premises in mind while evaluating a syllogism. It is closely related to but distinct from short-term memory, which is passive storage.
Working memory is the cognitive system that holds and manipulates information over short timescales — the few seconds during which you mentally hold a phone number while you walk to the keypad, or the moment you keep three premises in mind while evaluating a syllogism. It is closely related to but distinct from short-term memory, which is passive storage. Working memory adds active manipulation: rearranging, comparing, integrating, updating.
The dominant model of working memory is Alan Baddeley's, refined over four decades. It posits a central executive that allocates attention and coordinates subordinate stores, a phonological loop that holds verbal material, a visuospatial sketchpad that holds visual and spatial material, and an episodic buffer that integrates information across modalities and links to long-term memory. Each subsystem has a limited capacity (typically 3 to 7 chunks) and a limited duration (typically a few seconds without rehearsal).
Working memory capacity correlates with general intelligence at roughly r = 0.5 to 0.7 — one of the strongest cognitive correlates of g identified. Tasks that load heavily on working memory (reading span, operation span, n-back) are nearly as predictive of fluid-reasoning scores as fluid-reasoning tests themselves. This empirical finding has motivated extensive research on whether working-memory training can improve general intelligence. The current consensus, after a decade of mixed results, is that working-memory training reliably improves performance on the trained task and on closely related tasks, but transfer to general fluid intelligence is small and unreliable.
Working memory is the cognitive system most reliably degraded by acute states: sleep deprivation, alcohol, anxiety, and infection all reduce working-memory capacity within hours. It is also one of the cognitive systems most reliably affected by aging — capacity declines roughly linearly from the early 20s through the 70s, and the decline is strongest on tasks that require active manipulation rather than passive storage.
Because working memory is the bottleneck for so many real-world cognitive tasks — reading comprehension, mental arithmetic, multi-step planning, conversation in noisy environments — protecting and supporting it has practical value. The research-supported approaches are unsurprising: adequate sleep, regular aerobic exercise, low chronic stress, and the use of external aids (notebooks, calendars, lists) to offload information that does not need to be held in mind.