Hick's law
Hick’s Law (or the Hick-Hyman Law) is named after a British and an American psychologist team of William Edmund Hick and Ray Hyman. In 1952, the two set out to examine the relationship between the number of stimuli present and an individual’s reaction time to any given stimulus. Hick’s Law is therefore a simple logical deduction that the more options users are presented with, the longer it will take them to reach a decision. If users end up stuck in the decision-making process of “what next?”, they may become confused, frustrated, or even leave the website. The rule is sometimes neglected when the designer tries to include too much into a site or application. It is thus prudent to keep Hick’s Law to mind when analysing how many functions should be offered in a website and how this will affect the users’ overall approach to decision making.
The formula for Hick’s Law is defined as follows:
RT = a + b log2 (n)
“RT” is the reaction time, “(n)” is the number of stimuli present, and “a” and “b” are arbitrary measurable constants that depend on the task that is to be carried out and the conditions under which it will be carried out. “A” could be finding the right colour shirt online for someone, whilst “B” could be an onscreen advert from a clothing line in which people are modelling shirts.
Generally, the application of Hick’s Law is simple – reduce the number of stimuli and get a faster decision-making process — but there are exceptions to the rule. For example, a user may already have made a decision before seeing the stimuli. In that instance, the time it takes for him/her to act is likely to be less than if he/she had not already determined a course of action.
In terms of examples that utilise the benefit of the law, Google is one such example. The site limits decision-making for the user by giving two choices over search results; additional content is absent from the main page that could distract from the act of typing a keyword or require additional decision-making.
Apple’s TV remote control, meanwhile, is very minimalist and does not require significant memory; it therefore incurs much less cognitive load for users. By transferring complexity to the TV interface itself, information can be effectively organized and progressively disclosed within menus.
The website Slack uses a bot to engage users and prompts them to learn the messaging feature. But to prevent new users from feeling overwhelmed, Slack hides all features except for the messaging input. Once users have learned how to message via Slackbot, they are progressively introduced to additional features.
The designer often has to make compromises with Hick’s Law, as sometimes there is no avoiding complexity. For example, a DSLR camera has many more controls and options than a camera on a smartphone; thus the objective of Hick’s Law is to try and simplify the decision-making process, not eliminate that process entirely.
Separating the essential material from the secondary options is vital. When people arrive at the website, they are examining the product with a fresh perspective. The designer must decide what they will offer the users to get them to decide their next move. Good designers also try to employ Hick’s Law to respect their users’ time, thus ensuring a high-quality user experience.
One can see Hick’s Law in action in the navigation of almost any website. But if menus offered direct access to every link within the site, it could quickly overwhelm the visitor. For instance, if Amazon’s menus did that, it could take several hours to scroll through a menu. Designers therefore need to group menu items into broad categories instead. These should slowly expand as the users select options; the new categories then take users where they want to go.
With highly complex sites, the use of Hick’s Law requires further implementations of choice. Navigation items can be scattered throughout the design in small, discrete clusters. These will help narrow down huge volumes of information without overloading the user.
By studying eye-tracking patterns on a heat map of the site, this can help work out where future design changes might benefit from further applying Hick’s Law.
If a site has complex processes within it, Hick’s Law can be used to rationalise this by only presenting specific parts of that process at any one time on the screen. This then avoids displaying the entirety of the process in a long, complex form, and can break it down whilst also prompting users to register their e-mail and create a password.
In broader terms, there is an optimum point for most websites in terms of time spent looking. Too little time and the user has likely left without clicking CTAs; too much time and they may get caught up in information consumption and again fail.
However, whilst the simplification of decision-making can extend the time spent on a site, it might also reduce it. If the decision making is so simple that users make little progress towards their objectives each time they make a decision, they might be as likely to leave as users who find the decision-making process confusing.
Hick’s Law can also affect the number of page views that each user carries out. If the navigation menu is too complex, the number of page views is likely to be lower than if users were offered a navigation menu that better met their needs. Page views are, however, only important if the users are achieving their objectives while on site. It would be easy to construct a very deep menu system of binary choices in order to get to the desired information. Unfortunately, such a design would mean users would abandon the site long before getting to the information they needed.
In conclusion, the designer should follow these recommendations to avoid user frustration: -
- Minimise choices when response times are critical to decrease decision time.
- Break complex tasks into smaller steps in order to decrease cognitive load.
- Avoid overwhelming users by highlighting recommended options.
- Use progressive onboarding to minimize cognitive load for new users.
- Be careful not to simplify to the point of abstraction.
