Hick's Law
Decision time grows logarithmically with the number of equally likely choices, so the tenth option costs far less than the second.
Definition
Hick's Law (properly the Hick-Hyman Law) describes how long it takes to choose between alternatives. Reaction time rises with the logarithm of the number of options, not linearly: RT = a + b·log₂(n + 1). Doubling the options adds a fixed increment rather than doubling the time.
Established research. Originates in published research and has been replicated. The effect is real. Its size in your product still needs measuring.
On this plate
Reach for this when
- A single decision blocks the user from continuing.
- Options are unfamiliar and roughly equally attractive.
- You can set a sensible default for the majority case.
- A screen has accumulated options one release at a time and nobody has looked at the total.
Common mistakes
- Treating menu scanning as a Hick problem when it is a visual search problem.
- Adding hierarchy to shorten lists, which trades one decision for two.
- Ignoring that real options are rarely equally probable.
What the research actually measured
William Hick (1952) and Ray Hyman (1953) ran controlled reaction-time experiments. Participants responded to one of n stimuli, each equally likely, with a pre-learned response mapped to each one. Under those conditions reaction time tracked the information content of the stimulus set almost perfectly.
That setup matters. The law describes choosing among options you already know, that are equally probable, and that map one-to-one onto responses. It is a model of decision time under uncertainty, not a model of scanning an unfamiliar menu.
Applying it without breaking the interface
Do
- Reduce options at moments of genuine decision: pricing tiers, primary calls to action, destructive confirmations.
- Set a strong default so the common case is a confirmation rather than a choice.
- Group long lists into labelled categories so the reader makes one coarse decision then one fine one.
- Order options by likelihood when they are not equally probable. The law assumes equal probability, and real interfaces rarely have it.
Do not
- Hide frequently used items behind a submenu just to shorten the visible list.
- Apply it to search, filtering or browsing, where the user is scanning rather than deciding.
- Use it to justify removing functionality that a segment of users depends on. Move it, do not delete it.
- Quote a specific millisecond figure. The constants a and b are task and population specific.
Where it shows up in product work
The strongest practical use is in onboarding, checkout and destructive flows, where a single decision blocks progress and the options are genuinely unfamiliar. Splitting a fourteen-field signup into three short steps does not reduce total work, but it does reduce the number of decisions held in mind at once, which is a cognitive load argument as much as a Hick argument.
The weakest use is navigation. Global navigation is a recognition task supported by labels the user has seen before. Optimise it for scent and grouping rather than raw item count.
Reducing the decision without hiding the options
Deleting choices is the crude version and often the wrong one. These moves cut decision time while leaving the same capability reachable.
| Situation | Move | What it costs |
|---|---|---|
| Many options, one usually right | Set a default and let it be changed | The default now carries responsibility |
| Many options, genuinely different audiences | Segment first, then show the subset | Someone has to maintain the segmentation |
| Many options, all occasionally needed | Rank by frequency and put the tail behind more | The tail gets harder to find |
| Options that only make sense in sequence | Split into steps, each with few choices | More screens, and more places to abandon |
In practice
- i.
Pricing pages with three tiers
SaaS marketingThree named tiers with one visually recommended default turns a comparison into a confirmation. Adding a fourth tier is usually a business decision, not a UX one, and it measurably slows selection because the tiers stop being distinguishable at a glance.
- ii.
Remote control redesigns
Consumer hardwareStreaming remotes collapsed forty buttons into around a dozen by moving rare functions on screen. The decision cost of the common case dropped sharply. The rare functions became slower to reach, which was an accepted trade rather than an oversight.
- iii.
The settings screen that grew
Where the law arrives quietlyNo single release added more than two settings, and after two years the page held sixty. Hick's Law describes the cost of that page, and nothing in the review of any individual release would have caught it.
Commonly confused with
Close neighbours that get substituted for each other. The difference is stated first, then the condition that picks one over the other.
Miller's Law
LawWorking memory holds only a few chunks at once, which is why information is chunked.
Key difference
Hick's Law is about how long a choice takes when options increase. Miller's Law is about how much can be held in working memory, and is routinely misquoted as a limit on how many items a menu may hold.
Use Hick's Law when
- You are reasoning about how long a choice takes to make.
- The problem is an overloaded menu, filter set or pricing page.
- The fix is grouping, defaulting or staging the options.
Use Miller's Law when
- The reader has to carry something from one screen to the next.
- You are deciding how to chunk a code, number or instruction.
- The problem is recall, not selection.
Local chart
LAW·001 · Region I · Grid B2
This entry and the entries it is stated to connect with. Each line is labelled with what the connection means.
Sources
Where a source establishes something narrower than the popular reading of it, the note says so.
- [1]
On the rate of gain of information
W. E. Hick, Quarterly Journal of Experimental Psychology, 1952
The original reaction-time experiments establishing the logarithmic relationship.
- [2]
Stimulus information as a determinant of reaction time
R. Hyman, Journal of Experimental Psychology, 1953
Independent confirmation and generalisation, which is why the effect is properly the Hick-Hyman Law.
- [3]
Selection from alphabetic and numeric menu trees using a touch screen
T. K. Landauer and D. W. Nachbar, CHI, 1985
Evidence that broad shallow menus outperform deep narrow ones, complicating naive applications of Hick's Law.
Continue from here
Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.
Applies when you are designing
Why this works
The reasoning this entry rests on.
- Default EffectBIAS·004 · Cognitive bias
- Choice OverloadPSY·002 · Psychology
Hick's Law measures decision time. Choice overload describes what happens when the decision is abandoned instead.
- Cognitive LoadPSY·001 · Psychology
- Decision FatiguePSY·010 · Psychology
Applied through
Where this shows up as a concrete interface decision.
- DropdownCMP·019 · Component
- Radio GroupCMP·006 · Component
- SelectCMP·004 · Component
- ComparisonPAT·006 · Pattern
- NavigationPAT·001 · Pattern
Check your work
Review passes that test whether this was done properly.
- Form UX ChecklistCHK·001 · Checklist
Short definition
The one-paragraph version, for when that is all you need.
- Progressive DisclosureTERM·016 · Term
Related concept
Connected closely enough to change how you apply this.
- Aesthetic and Minimalist DesignHEUR·008 · Heuristic
- Recognition Over RecallHEUR·006 · Heuristic
- Tesler's LawLAW·005 · Law
- Occam's RazorPRIN·001 · Principle
- Progressive DisclosurePRIN·003 · Principle