Miller's magical number seven
Also known as: Magical number seven, The magical number seven, plus or minus two
Immediate memory holds only about seven items at once.
What it means
Miller's famous claim is that the span of immediate memory and of absolute judgment is limited to about seven plus or minus two items, a surprisingly small and roughly constant capacity across many kinds of material. His key insight was that the limit applies to chunks, not raw stimulus information, so recoding into larger units is the route to handling more. Later work argued the true capacity is smaller — closer to four chunks — once rehearsal and long-term support are controlled. The paper is among the most cited in psychology and helped launch the information-processing approach to cognition. It remains the touchstone for discussions of working-memory capacity.
Examples
Most people can repeat back about seven random digits but stumble much beyond that without chunking.
A sort code is read as three pairs and a card number in blocks of four — the same digits, resliced into fewer chunks so they fit in the mind at once.
A beginner tracks six separate finger positions; the experienced guitarist thinks 'G chord' — one chunk where there were six items, freeing capacity to follow the song.
First described in George Miller (1956).