cognitive psychology
Hick's law
The more choices you offer, the longer a decision takes - and it climbs with the logarithm of the number of options, not in a straight line. Choices carry a time cost, not just a space cost.
The demo
Four rounds. Each time, find one named item in the menu and click it - but the menu keeps growing: 2 options, then 4, then 8, then 16. Every choice is timed.
Find and click:
What this demo shows (text version)
You're shown a menu and asked to click one named item. The menu grows each round - 2, 4, 8, then 16 options - and each choice is timed.
The reliable result: your time goes up as the menu grows, but far more slowly than the option count does - roughly with its logarithm. Doubling from 8 to 16 options adds much less time than the first jump from 2 to 4. That curve is Hick's law: it's the case for short, well-grouped menus, and the warning that piling on choices quietly taxes every decision.
Your time barely doubled while the options went up eightfold - that curve is Hick's law. It's why a tidy menu of five beats a wall of fifty, and why "more options" isn't the same as "more usable".
Hick's law gets weaponised to justify stripping every interface to three buttons. But grouping beats hiding: a long restaurant menu split into sensible sections is fast, because you choose a section first, then a dish. You're paying the log cost twice on small sets instead of once on a huge one.
It only really holds when the options are unfamiliar and equally likely. The moment something becomes a habit - the "Send" button you've hit a thousand times - the search collapses and the law stops applying. Design for the first-timer and the regular at once.