UX laws are an invaluable tool, providing guidelines for designers that ensure we don’t have to continually reinvent the wheel when crafting experiences for the web.

However, UX laws tend to be devised by scientists and psychologists — people who are more than comfortable with the exceptions and allowances of academic language. By the time they filter down to us in the trenches, the language has invariably been over-simplified, and the wisdom behind the idea diluted.

Today we’re going to look at seven well-known and commonly cited rules of UX design that too many designers get wrong.

1. Jakob’s Law

Jakob’s Law, named for the UX researcher Jakob Nielsen, states that users spend most of their time on other sites and as a result prefer sites that work the same way as the sites they already know.

Jakob’s Law has often been used to limit experimentation and encourage the adoption of common design patterns in the name of usability.

However, the word ‘prefer’ is hugely loaded. While it’s true that a user will more easily understand a familiar design pattern, they do not necessarily prefer familiar experiences.

It has been widely proved that new experiences boost our mood and that new experiences improve our memory. If your goal is a memorable site that leaves users with a positive impression, introducing novelty is a sound decision.

2. Goal Gradient Hypothesis

The Goal Gradient Hypothesis assumes that the closer users are to their goal, the more likely they are to complete it.

It’s an attractive theory, especially in e-commerce, where it is often used to justify simplifying the initial purchase process and postponing complexity to move users along the funnel — a typical example is leaving shipping charges until the final step.

However, anyone who has studied e-commerce analytics will know that cart abandonment is a huge issue. In North America, shopping cart abandonment is as high as 74%.

We don’t always know what the user’s goals are, and they may not match ours. It may be that users are treating your shopping cart as a bookmark feature, it may be that they have a last-minute change of heart, or they may be horrified by the shipping charges.

While providing a user with an indication of their progress is demonstrably helpful, artificially inflating their proximity to your preferred goal may actually hinder conversions.

3. Miller’s Law

Never in the whole of human history has any scientific statement been as misunderstood as Miller’s Law.

Miller’s Law states that an average person can only hold seven, plus or minus two (i.e., 5–9) items in their working memory. This has frequently been used to restrict UI navigation to no more than five items.

However, Miller’s Law does not apply to items being displayed. While it’s true that too many options can lead to choice paralysis, a human being is capable of considering more than nine different items.

Miller’s Law only applies to UI elements like carousels, which have been widely discredited for other reasons.

4. Aesthetic-Usability Effect

Edmund Burke once said, “Beauty is the promise of happiness.” That belief is central to the Aesthetic-Usability Effect, which posits that users expect aesthetically pleasing designs to be more usable.

Designers often use this as a justification for grey-on-grey text, slick animations, and minimal navigation.

Critical to understanding this is that just because users expect a design to be usable does not mean that it is or that they will find it so. Expectations can quickly be dashed, and disappointment often compounds negative experiences.

5. Peak-End Rule

The Peak-End Rule states that users judge an experience based on how they felt at the peak and the end, rather than an average of the experience.

Designers commonly use the Peak-End Rule to focus design resources on the primary goal of each experience (e.g. adding an item to a cart) and the closing experience (e.g. paying for the item).

However, while the Peak-End Law is perfectly valid, it cannot apply to open experiences like websites when it is impossible to identify a user’s starting or ending point.

Additionally, it is easy to see every interaction on a website as a peak and even easier to make assumptions as to which peak is most important. As such, while designing for peaks is attractive, it’s more important to design for exceptions.

6. Fitts’ Law

In the 1950s, Paul Fitts demonstrated that the distance to, and size of a target, affect the error rate of selecting that target. In other words, it’s harder to tap a small button and exponentially harder to tap a small button that is further away.

UX designers commonly apply this law when considering mobile breakpoints due to the relatively small viewport. However, mobile viewports tend not to be large enough for any distance to affect tap accuracy.

Fitts’ Law can be applied to desktop breakpoints, as the distances on a large monitor can be enough to have an impact. However, the majority of large viewports use a mouse, which allows for positional corrections before tapping.

Tappable targets should be large enough to be easily selected, spaced sufficiently, and tab-selection should be enabled. But distance has minimal impact on web design.

7. Occam’s Razor

No collection of UX laws would be complete without Occam’s Razor;unfortunately, this is another law that is commonly misapplied.

Occam’s Razor states that given any choice, the option with the least assumptions (note: not necessarily the simplest, as it is often misquoted) is the correct choice.

In an industry in which we have numerous options to test, measure, and analyze our user interfaces, you shouldn’t need to make assumptions. Even when we don’t need extensive UX testing, we can make decisions based on other designers’ findings.

Occam’s Razor is a classic design trap: the key to avoiding it is to recognize that it's not your assumptions that matter, it’s the users’. As such, Occam’s Razor applies to a user’s experience, not a design process.