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Laws of UX – Part Two

June 7, 2021

Continuing from our part one blog, I’d like to continue our rundown of the final five laws of UX. If you haven’t already checked out part one, it is available to read here.

6. Miller’s Law

The average person can only keep 7 (plus or minus 2) items in their working memory.

During the 1950s, Psychologist George Miller claimed that our immediate memory span and judgment had a limit of around seven elements of information at a time. While this law may act more like a guideline, it is relevant to specific ways of utilising our short-term memory when browsing online.

Regardless of the number of units, what Miller’s Law should guide within UX design is to chunk information into logical groupings. This helps our user absorb information quickly and easily. To put this into simple terms, Miller’s Law should be used when you’re looking at categorising and grouping information to help a user find exactly what they’re looking for.

7. Pareto Principle

The Pareto principle states that, for many events, roughly 80% of the effects come from 20% of the causes.

Also known as the ’80/20 Rule’ or the ‘Law of the Vital Few’. The Pareto principle was originally penned by Wilfredo Pareto. He noticed that 80% of the land in Italy was owned by just 20% of its population. This law can provide an insightful analysis application within UX. Without getting intensely hung up on the numbers, the crux of the principle can be used to conduct research. If you can focus on the 20% of elements people use the most within, for example, a website, it usually means that the majority of users are landing there. Where we can see this in action, with sites that may pre-populate forms without prompting. Such as hotel booking websites. They will pre-populate the most popular number of nights staying and the number of people staying within the search bar. Because, during their UX research, around 20% of bookings will fit these criteria.

8. Parkinson’s Law

Any task will inflate until all of the available time is spent.

Initially, this law was published by the Economist in the 50s by Cyril Northcote Parkinson. Without going into great details about its originality, the principle can be applied to UX design. In its purest form; If you wait until the last minute, it only takes a minute to do. The law applies to inflation and deflation of time concerning the task we’re applying that time to. We can use this within UX design in the assumption that our users don’t have a great deal of time to complete a task. Or that they will bend the time to suit their needs. In this case, we must make sure that instructions and actions are transparent to complete and follow quickly. It’s a simple law that sounds like a bit of a no-brainer when we apply it to the design.

9. Serial Position Effect

Users have a propensity to best remember the first and last items in a series.

Initially coined by Herman Ebbinghaus, the Serial Position Effect suggests that the position of an item will affect how accurately we recall that item. This concept explains that terms at the beginning and end of a sequence are recalled more accurately than items that sit in the middle. We can apply this principle very simply in UX design by prioritising things to follow this way of thinking. Most notably you can see this within the design of header navigation items. ‘Contact’ will usually be at the end of the list where the company are looking to gain enquiries online. Websites such as charities may have a ‘Donate’ button at the start of their navigation list. It’s a simple way to gain results without too much investment.

10. Tesler’s Law

Tesler’s Law, also known as The Law of Conservation of Complexity, states that for any system there is a certain amount of complexity that cannot be reduced.

Larry Tesler, while working for Xerox PARC in the 80s, realised that users interact with applications in a way that is just as important as the application itself.

The law states that every application has an element of complexity that can’t be removed and instead should be dealt with in UI or product development. It ultimately poses the question of who should deal with complexity, the user or the person designing the interaction. If the user is interacting with a website for a complex piece of software, for example, should their interaction reflect the complexity of the software? Or should the user be given a more straightforward journey to that point? It is a long-debated idea that should be dealt with within the context of the product you are designing for.

The science behind good UX relies on understanding how people think. Our UX team have the experience and insight to optimise sites and drive users to convert. Contact us today if you’re interested in finding out more about how UX design can improve your site.




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