Hick’s Law states that the time it takes someone to make a decision increases with the number and complexity of choices available. More options mean slower decisions. The relationship isn’t linear, though. Decision time increases logarithmically, meaning that going from 2 choices to 4 adds more time than going from 20 to 22. The law is one of the most widely applied principles in user experience design, human factors engineering, and cognitive psychology.
The Math Behind the Law
Hick’s Law is often written as RT = a + b × log₂(n), where RT is reaction time, n is the number of equally probable choices, and a and b are constants that vary depending on the person and the task. The “a” represents baseline processing time (perceiving a stimulus and physically responding), while “b” reflects how much each additional choice slows you down.
The logarithmic relationship is the key insight. If choosing between 2 options takes you roughly 0.5 seconds, choosing between 4 doesn’t take a full second. It might take around 0.65 seconds. This is because your brain doesn’t evaluate each option one by one. Instead, it narrows possibilities by halving them, similar to how you’d search a sorted list by starting in the middle rather than scanning from the beginning. Each doubling of options adds roughly one equal “step” of processing time rather than doubling the total.
Where the Law Comes From
British psychologist William Edmund Hick published the foundational work in 1952, and American psychologist Ray Hyman extended it the same year. Their experiments were straightforward: participants faced a set of lights, each paired with a response key, and had to press the correct key as quickly as possible when a light turned on. As the number of light-key pairs increased, reaction times rose in a predictable logarithmic curve. The finding was so consistent across participants that it became one of the few genuine “laws” in experimental psychology, sometimes called the Hick-Hyman Law.
When Hick’s Law Applies (and When It Doesn’t)
Hick’s Law works best under specific conditions. The choices need to be roughly equal in familiarity, and the person needs to actually be deciding between them rather than searching for something specific. A person scanning a restaurant menu with 50 items they’ve never seen will experience the slowdown. A person opening their phone’s contact list to call their mom will not, because they already know exactly what they’re looking for.
The law also breaks down when choices aren’t equally probable. If you’re a driver approaching an intersection and the light is green, you technically have choices (stop, go, slow down), but “go” is so dominant that the other options barely register. Expertise compresses decision time in a similar way. A chess grandmaster looking at a board with dozens of possible moves doesn’t experience the same logarithmic slowdown as a beginner, because pattern recognition lets them skip straight to a small set of strong candidates.
Highly familiar or well-practiced responses also bypass the law. Typing on a keyboard involves choosing from 26+ keys, yet experienced typists don’t slow down proportionally because the decisions have become automatic through practice.
Hick’s Law in UX and Product Design
The most common modern application of Hick’s Law is in designing interfaces. When users face too many options on a screen, they take longer to act, and in many cases they don’t act at all. This phenomenon, sometimes called choice overload or decision paralysis, goes beyond simple reaction time into emotional territory: too many choices can feel overwhelming and reduce satisfaction with whatever is eventually chosen.
Designers use several strategies informed by the law:
- Progressive disclosure. Rather than showing all options at once, reveal them in stages. A settings menu with five categories, each containing five options, feels more manageable than a single screen with 25 controls, even though the total number of choices is identical.
- Categorization and grouping. Organizing 30 items into 5 clear groups lets the brain do what it naturally does: eliminate categories first, then choose within the winning category. This effectively turns one 30-option decision into a 5-option decision followed by a 6-option decision.
- Smart defaults. Pre-selecting the most common choice removes the decision entirely for the majority of users. The option to change is still there, but most people never need it.
- Highlighting recommended options. Pricing pages that mark one plan as “most popular” are directly applying Hick’s Law. By making one option more visually prominent, they reduce the effective number of choices the brain has to weigh.
Google’s homepage is the classic example. In an era when competing search engines cluttered their pages with links, categories, and portals, Google presented essentially one choice: type what you want. That radical simplicity made the decision time nearly zero.
Hick’s Law in Everyday Life
The law shows up far beyond screens. Restaurants with shorter menus tend to produce faster ordering and, counterintuitively, higher customer satisfaction. Grocery stores that reduce the number of jam varieties on a shelf from 24 to 6 see dramatically more purchases, a finding from a well-known study by psychologists Sheena Iyengar and Mark Lepper. Emergency procedures are designed with minimal branching decisions because reaction time matters most when stakes are highest. Cockpit controls, military protocols, and first-aid training all reflect Hick’s Law by limiting the number of choices a person faces under pressure.
In sports, athletes use the principle instinctively. A basketball player with three open teammates will take slightly longer to pass than one with a single obvious target. Defensive strategies in many sports aim to present the opponent with more options, not fewer, because more options slow their response. A quarterback reading a complex defensive formation faces more choices about where to throw, and those extra milliseconds of processing time give the pass rush more time to arrive.
Common Misapplications
Hick’s Law is frequently oversimplified into “fewer choices are always better,” which misses important nuance. Reducing choices only helps when the user is genuinely deciding between alternatives. If someone is searching or browsing (scanning a list of search results, for instance), more options can actually be better because the task isn’t really a decision. It’s a recognition task, and Hick’s Law doesn’t govern recognition in the same way.
Forcing too few options can also backfire. If you simplify a navigation menu so aggressively that users can’t find what they need, you’ve traded one problem (slow decisions) for a worse one (no path forward at all). The goal isn’t minimum choices. It’s minimum unnecessary choices. Every option should be distinct, clearly labeled, and relevant to what the user is trying to accomplish at that moment.
Another frequent mistake is applying the law to complex, high-stakes decisions like choosing a health insurance plan or a mortgage. These decisions involve weighing tradeoffs across multiple dimensions, comparing features, and predicting future needs. Hick’s Law was derived from simple reaction-time tasks with clear right answers. It describes the time cost of having more options, but it doesn’t capture the full psychology of complex decision-making, where factors like risk aversion, information overload, and regret avoidance play much larger roles.