Laws of Perception · principle
Miller's Law
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The average person can hold only about seven (plus or minus two) items in working memory at once. The practical takeaway isn't a hard limit on menu length — it's chunking: group related information into a few meaningful units so the mind can hold and process it comfortably.
See it on a real screen
Working memory holds only a handful of items at once, so the same 16 digits become effortless once they're chunked into four groups — exactly how every card field and phone number is formatted.
Where it comes from
In 1956, Princeton psychologist George A. Miller published 'The Magical Number Seven, Plus or Minus Two', one of the most cited papers in psychology. Reviewing experiments on how many distinct tones, digits, or items people could reliably recall, he kept finding the same ceiling — around seven — and noted that the mind gets around it by 'chunking' raw items into larger meaningful groups. The number is famous, but Miller himself was more interested in chunking than the seven, and the '7 items' rule is widely over-applied: it's an argument for grouping, not a cap on how many links a menu may have.
Origin: Miller's 1956 working-memory recall experiments
In the wild
- Phone numbers
Written as 0XX-XXX-XXXX rather than a 10-digit run — the dashes chunk the number into memorable groups.
- Card entry fields
A 16-digit card number is split into four groups of four, so each chunk fits comfortably in working memory as you type.
- Dashboard cards
Grouping metrics into a handful of labelled cards instead of one long list reduces the load of scanning them.
Further reading
Don't just read it — feel it.
Play the 3-minute game and let your own reactions prove the law.
Play the lesson