Hick’s Law is the principle that the more choices you present a user with, the longer it takes them to make a decision. The time it takes a person to make a decision increases logarithmically with the number of choices you offer them. This should provide a warning to designers and project managers not to build too much functionality into a site or application. It is often forgotten because of the desire to offer more than the competitor’s site.
Hick’s Law is also named after the British and American psychologists William Hick and Ray Hyman. They conducted research in 1952 to establish the relationship between the number of choices a person is presented with and the individual’s reaction time. The more choices you offer people the longer it takes them to make a decision on which one to select
The research by Hick and Hyman led to a formula to define Hick’s Law:
RT = a + b log2 (n)
“RT” is the reaction time, “(n)” is the number of stimuli, and “a” and “b” are the unique measurable constants that depend on the task being completed and the conditions under which they are being undertaken. “A” could be a leaving gift for your boss. “B” could be an email chain with other members of the team to discuss what to buy them.
Implications for conversion rate optimisation:
- Minimise the number of calls to action and links on each page.
- Follow established web conventions to allow users to learn from past experience.
- Avoid mission creep by adding more options and features just because you can.
- Focus on user behaviour and needs rather than what your competitors are doing.
- Use visual cues to give clear prominence to the key conversion assets.
- Minimise clutter to avoid cognitive strain by eliminating distractions.
Finally, Hick’s Law provides scientific evidence to support conversion rate optimisation principles. This includes using design to minimise clutter and distractions and also having a clear hierarchy of information on a page. By carefully limiting the number of options or features to visitors we can reduce time spent making decisions and improve overall customer satisfaction.
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