B-01 · Memory Systems
Sequences of symbols appear once, then vanish. The door advances only while your memory holds. How far can you go?
Experimental design
Adaptive staircase (within-subjects); memory span procedure
Digit span
Longest sequence of items recalled in correct order on a majority of trials
Working memory capacity
Limit on items held in an active, manipulable store (often ~4 chunks when rehearsal is controlled; Cowan, 2001)
Chunking
Recoding individual items into larger meaningful units to expand effective capacity
Magical number seven
Miller's (1956) synthesis that immediate memory span clusters near 7 ± 2 items before chunking.
Phonological loop
Baddeley's subsystem for maintaining verbal sequences via subvocal rehearsal.
Articulatory suppression
Interfering with rehearsal (e.g., repeating an irrelevant word) to isolate storage capacity.
Difficulty
IntroEstimated time
9 minutes
Paradigm
Digit span
First published
1956
Working memory, the mental workspace where you hold and manipulate information, has a sharply limited capacity. Most adults can hold about seven digits, and about four independent chunks, before the sequence collapses.
George Miller's 1956 paper 'The Magical Number Seven, Plus or Minus Two' is among the most cited in psychology. Reviewing absolute-judgment and immediate-memory studies, Miller observed a recurring capacity near seven items and, crucially, that the unit is the chunk, not the bit: recoding items into larger meaningful units expands effective span. Later work by Nelson Cowan revised the pure capacity estimate to about four chunks when rehearsal and grouping are controlled.
Miller, G. A. (1956). The magical number seven, plus or minus two: Some limits on our capacity for processing information. Psychological Review, 63(2), 81–97.