Remember when your mother warned you not to run down the stairs because you could fall and hurt yourself? Or when you held your palm over a candle’s flame and started feeling the burn? The “laws of UX” are similar—they are cause and effect relationships where one event (the cause) makes another event happen (the effect). Whether a designer acknowledges them or not, the “laws” rule and operate—and will affect the effectiveness of a design.

Take Miller’s Law, for example, which states that “the average person can only keep around seven items in their working memory.” When the rule is disregarded, people are forced to think more than they should have to. UX professionals refer to this phenomenon as cognitive overload.

Ignoring Miller’s Law can have negative consequences that may impede the UX, i.e., if there are too many things people have to remember, it could cause frustration and decision paralysis.

Miller's Law example

Presenting too many choices in a hard-to-comprehend format may overload the user's cognitive capacity, causing frustration and decision paralysis. (Source: UI Patterns)

A cousin to Miller’s Law is Hick’s Law, which states: “The time it takes to make a decision increases with the number and complexity of choices.” It’s easy to see how they’re related. In a poorly designed scenario, both of these laws could be violated at the same time by a UI that presents too many choices and asks people to remember too many things when trying to complete a task.

Then there’s Fitts’ Law. Specific to human-computer-interaction (HCI) on desktops, Fitts’ Law predicts that “the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target”—for example, how large a button is, and how far it is from the cursor’s position in the UI.

Fitts' Law UI example formula demonstration

Many UX designers forget that Fitts’ Law—as well as many other UX laws—can also be used creatively by placing destructive features in a UI in a difficult-to-reach position—such as a reset form or the “cancel” button on a web form.

It’s important to remember that, typically, Fitts’ Law doesn’t apply to mobile. However, even though there is no cursor to travel to a target location, a designer can use the distance from one tap to another to either impede or assist an interaction. For example, a “logout” icon can be placed at the top of the mobile screen, and the confirmation could come up on the bottom.

A great customer experience is based on trust and meaningful, consistent interactions. Any designer worth their salt must consider cognitive psychology and the effect of their work on their intended audience. For example, if one considers a bank with over 25 million mobile customers it can be easily seen how ignoring the laws of UX could seriously hinder their app’s UX, and consequently affect their bottom line.

Taken collectively, observing these laws of UX can help guide a digital designer toward creating the most effective design for any given product. Even though they are not actual laws, but rather tried and true cause and effect relationships, UX designers should nevertheless, take notice of the driving forces behind the laws of UX in order to design superior products.

Infographic of the Laws of UX

Understanding the Basics

Why is Fitts' Law important?

Fitts' Law demonstrates how to ease interactions through the careful sizing and positioning of interface elements. It states: The time it takes to acquire a target is a function of the distance to and size of the target. It is particularly important when designing buttons and other clickable on-screen elements.

About the author

Miklos Philips, United Kingdom
member since April 26, 2016
Miklos is a principal lead, product designer and strategist with more than 18 years of experience. As a full-spectrum product designer, he mediates between user needs, business objectives, and technical feasibility resulting in product designs that work for the intended audience and impact the bottom line. [click to continue...]
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Comments

butlerhouse
At risk of repeating the obvious, yes every UI designer should be well versed in these laws as well as gestalt design theory, first principles of interaction design and value opportunity attributes. With consumers relying more and more on their parietal lobes and pattern recognition, it's more important than ever to consider the science of how we process information.
Rome
Millers Law #4 is actually not true. It has been debunked. The actual number is 4 plus/minus 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864034/ Laws are made to be broken?
Sylvain Gravel
Effective writeup, good work. I'll print the great infographic and hang it on my wall!
Jacque Harper
See also http://www.knosof.co.uk/cbook/misart.pdf "The 7 +/- 2 Urban Legend" by Derek Jones. The limit of human memory varies with the kind of information being stored and other factors. It's not as simple as "n plus or minus x." When I posted about this on LinkedIn, on commenter noted "we should be designing for recognition, not recall."
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About the author
Miklos Philips
User Experience Designer
Miklos is a principal lead, product designer and strategist with more than 18 years of experience. As a full-spectrum product designer, he mediates between user needs, business objectives, and technical feasibility resulting in product designs that work for the intended audience and impact the bottom line.