Choice time grows with the logarithm of the number of equally likely options.
T = b·log₂(n+1)
documentedA named, findable source says this. Why: Hick 1952 and Hyman 1953 are published reaction-time experiments.
The same task, built twice
Both panes below are real interfaces. They respond, they can be got wrong, and each
is timed from your first move in it. The times are not a study — two panes, one reader,
no controls. They are here to make a difference you can feel into a number you can see, and
nothing is recorded or sent anywhere.
Your task
Select Portugal as your country.
Breaks it—
All 103 options, flat, one glance, no order you can exploit. The list is alphabetical, which helps — remove that and it becomes unusable, which is Hick–Hyman's actual claim.
Keeps it—
Most people here choose
Or find yours
The eight that cover most traffic first, then a typed filter over the rest. Choices are not removed; they are staged, so the first decision is between two small sets rather than one large one.
What to watch Count the number of decisions, not the number of options. The right-hand pane still contains every country — what changed is that you never had to consider all of them at once.
The principle
OriginW. E. Hick (1952) and Ray Hyman (1953) — reaction-time experiments on stimulus–response choice.
EvidenceHolds cleanly for simple, practiced, equally weighted choices — which is why command menus and remote controls benefit from pruning.
Limits & misuseThe most over-quoted law in design. It does not apply to reading a menu of unfamiliar options (that's visual search, roughly linear), and it never said "fewer options are always better" — a well-grouped fifty beats a random eight. Citing Hick to delete features is rhetoric wearing a formula.