Hick’s and Fitt’s laws: Two important psychological principles to consider when designing navigational menu structures

Most web-based or mobile applications are organized in some type of hierarchical menu structure. Company information is usually located in an ‘about us’ tab, Products and Services each have a tab, etc.

Some company websites, for example, provide a menu structure that is initially simple, but then may require several more interactions to navigate down the tree to the target information.

See for example Verizon.com:

The initial menu structure has only 3 choices, Wireless, Residential, and Business. Once you made a choice the system provides more information and more choices related to the selection until you’ve finally reached your target.

Other companies prefer the mega-menu approach, where a huge menu system is presented, and once the item is found, a single interaction is required to find the target.

See for example Cisco:

The Cisco top level menu has 5 main choices, but as shown above the single choice can present a mega menu with a plethora of information to choice from.

Given that menu items are often selected by indicating one of several alternatives in each of several different types of successive hierarchically organized menus, and given that the total set can be meaningfully subdivided in many different ways, what menu structure is optimal?

Two important cognitive psychological principles should be considered when making the design decisions for this very important part of a user interface. The first is Hick’s Law, the second is Fitt’s Law.

Hick's law (Welford, 1980) states that mean response time in simple decision tasks is a linear function of the transmitted information. Simply put this means that the amount of time it takes to make a decision is related to the number of choices that are presented. The more things that there are to choose from, the longer it will take to make a decision.

Restaurants often have some of the same issues as software developers. Have you ever been to a restaurant that has a menu the size of a phone book? I can remember spending way too long trying to decide what to eat at Canter’s Deli http://www.cantersdeli.com late one night after hanging out in their Kibitz room.

Broader menus necessarily require a decision among more alternatives. This decision can increase the cognitive load that is placed upon users.

Fitts's law (1954) states that mean movement time is a function of the log of distanced over width of target. This is one of the most widely cited/used theories in the user experience field. It basically proposes that people can quickly find items on the screen based upon their size and their proximity to the current focus of attention.

Fitt’s law also applies to the decision process of deciding what item to select, but in a different way then Hick’s law. Fitt’s law states that people can find things easier if they are larger and if they are closer to the current portion of the screen that the user is looking at.

Experts of SEO and site conversion should often apply Fitt’s law when deciding where to place the “call to action” that tries to grab the attention of the user and drive them to making a choice.

So how do you design an effective and efficient navigational menu structure? Well the answer of course is it depends. It depends on the number of items and levels of your hierarchical tree. It depends on the number of ‘call to actions’ or specific products or services you want to promote.

Keep in mind that it is often perceived to be easier to make several easy decisions than it is to make a single difficult one.

Design the process of traversing down your hierarchical tree to be a short series of small decisions. Don’t have too many items to choose from (Hick’s law) and make sure the process of choosing is as easy as possible by keeping things nearer to the user focus of attention (Fitt’s law).

Understanding and integrating each of these two laws, as well as many other principles of cognitive psychology, can help inform a strategic user experience plan that focuses on the cognitive skills of users to provide better experiences and positively impact business ROI.