cognitive psychology
Hick's law vs Miller's law
What's the difference between Hick's law and Miller's law?
Both are about "how many", but they measure different things. Hick's law is about choosing - decision time grows with the number of options. Miller's law is about holding - working memory keeps only about seven chunks at once. One is speed of choice; the other is capacity of memory.
Also known as: hicks law vs millers law, miller's law vs hick's law
The demo
One control, two laws. Drag the number of items and watch each panel react - Hick's measures how long it takes to choose, Miller's how much you can hold in mind. The same count, two different limits.
Hick's law - time to choose
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Choosing gets slower with the log of the count - a smooth curve, no hard ceiling.
Miller's law - working memory
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Holding maxes out around seven chunks, then overflows.
Drag the slider and watch the two laws diverge.
What this demo shows (text version)
A slider sets a number of items from 2 to 12, feeding two panels. The Hick's law panel shows the time to choose one option, which rises with the logarithm of the count - so going from few to many options slows decisions down along a smooth curve that never becomes impossible.
The Miller's law panel shows working-memory load as a meter filling toward about seven chunks; past seven it tips into "over capacity". The same number drives two different limits - speed of choosing versus capacity of holding - which is why the two laws are often confused. Hick's is for problems of choice; Miller's is for problems of memory.
Drag the count up and watch them part ways: Hick's time climbs in a gentle curve (deciding gets slower, but never impossible), while Miller's memory hits a wall around seven and tips into overload. Same number feeding two quite different limits - which is exactly why people muddle them.
When to reach for which: invoke Hick's law when the problem is choosing - a bloated menu, a wall of options, a checkout with too many paths. Invoke Miller's law when the problem is remembering - a code to carry between screens, a multi-step form, anything that asks people to hold information in their head.
The common myth muddles them into "seven is the magic number of menu items". It isn't: Hick's law has no magic number (the curve is smooth, and grouping beats a hard cap), and Miller's seven is about memory chunks, not how many links a navbar may have. Keep them straight and you'll apply each where it actually bites - see [Hick's law](/entries/hicks-law/) and [Miller's law](/entries/millers-law/).