Question
How many things can working memory hold?
Short answer
About four chunks, according to the best-known modern estimate. George Miller’s famous "seven, plus or minus two" from 1956 was later described as a rough estimate rather than a true limit. In 2001, Nelson Cowan reviewed the evidence and put the central capacity of short-term memory at about four chunks on average.
Want your own number? The test is 25 visual puzzles, about 12 minutes, no sign-up.
Seven, plus or minus two
In 1956 George Miller published one of psychology's most cited papers. He argued that the spans of absolute judgment and immediate memory severely limit how much information we can take in and keep, and that grouping input into chunks stretches that bottleneck (Miller, 1956). The title phrase, the magical number seven plus or minus two, became the popular answer to how much we can hold in mind.
The modern estimate: about four
Later research tried to measure the limit while preventing people from rehearsing or chunking. Reviewing that work, Nelson Cowan concluded that the central capacity limit averages about four chunks (Cowan, 2001). He also noted that Miller's seven was meant more as a rough estimate and rhetorical device than as a real capacity limit (Cowan, 2001).
| Estimate | Source | What it measured |
|---|---|---|
| About 7 (plus or minus 2) | Miller, 1956 | Immediate memory span, with chunking allowed |
| About 4 chunks | Cowan, 2001 | Central capacity, with rehearsal and chunking limited |
Try one · Logical Reasoning
Which tile completes the second pair?
Tap the option you think is right, or show the answer.
Show the answer
The missing panel shows a large outlined pentagon on its own (option 3).
How to solve it
- Compare the first two panels and name exactly what changed.
- The whole figure turns a quarter turn clockwise.
- The large shape becomes outlined.
- Nothing else changes.
- Apply the same changes to the third panel: a large solid pentagon on its own.
- So the missing panel shows a large outlined pentagon on its own.
That was 1 puzzle. The full test has 25.
Why it matters for IQ puzzles
A limit of about four chunks explains why hard puzzles feel hard. A matrix puzzle with three changing features, plus the answer you are testing, can fill the workspace. Working memory is linked to general intelligence: one meta-analysis of 86 samples found a correlation of about 0.48 (Ackerman et al., 2005). See is IQ related to memory and working memory.
Making the most of four
You cannot widen the slot much, but you can use it well. Check one rule at a time, name patterns in a word or two so they become single chunks, and eliminate answer choices as you go. The matrix reasoning guide and the puzzle library show this step by step.
Sources
- 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. doi.org/10.1037/h0043158
- Cowan, N. (2001). The magical number 4 in short-term memory: A reconsideration of mental storage capacity. Behavioral and Brain Sciences, 24(1), 87-114. doi.org/10.1017/S0140525X01003922
- Ackerman, P. L., Beier, M. E., & Boyle, M. O. (2005). Working memory and intelligence: The same or different constructs? Psychological Bulletin, 131(1), 30-60. doi.org/10.1037/0033-2909.131.1.30