Introduction

In an era where digital experiences shape our daily interactions and consumer decisions, it pays to understand the core principles of UX (user experience) design.

While UX principles come in many shapes and sizes, there is one particularly interesting strand called ‘heuristic laws’. These laws reflect how our brains make decisions by way of mental shortcuts.

Among these are four major laws that shape how our brains process information and make decisions:

1. Fitt's Law

2. Hick's Law

3. Jakob's Law

4. Miller's Law

Fitt's Law: The Ease of Interaction

The NordVPN landing page uses bright red buttons to draw attention to the primary CTA: user sign-up

Fitt’s law highlights the relationship between the size and distance of a target and the speed and frequency with which someone interacts with it. In other words:

• The greater the distance to the target, the longer the pointer will take to reach it;

• The larger the target, the shorter the movement time to it

The implication for UX design is that, if you want someone to interact with a certain object (e.g. a ‘Buy Now’ button), you should make it bigger and ‘closer’ (or more obvious) to the user. When implemented properly throughout a website, this law can lead to significantly higher conversion rates.

The name of the game here is minimising brain effort; if given the option, humans will always roll with ‘System One’ (automatic, low-effort, instinctive) thinking. So, if you put big, shiny objects in all the right places, you can limit engagement from the more rational, discerning ‘System Two’.

On the NordVPN website, the primary CTA (call to action) — getting users to sign up to their free trial — is made obvious by the bright red colour of the buttons, which glaringly contrast with everything else on the page. As the eye is naturally drawn to these buttons, you’re more likely to click on them. This layout is replicated on the vast majority of SAAS websites.

Hick's Law: Simplifying Choices

The quiz on Vitl’s site is broken down into a number of bite-sized questions spread across a number of different pages

Hick’s Law reflects the relationship between choice and decision-making: as the number of options increases, so does the time required to make a decision. Ever been to one of those restaurants that serves 3,829 mains and 812 sides? If so, did it take longer than usual to pick your meal?

To streamline the user experience, it’s important to reduce decision fatigue by simplifying choices and minimising cognitive overload. This can be achieved through:

• Categorisation

• Gradual reveal of information (aka ‘progressive disclosure’)

• Intuitive navigation paths

If you go onto Vitl’s website, you will be asked to take a health quiz before being sent your tailor-made supplement package. This quiz, by internet-age standards, is actually quite long (round about five minutes).

Thanks to its understanding of Hick’s Law, however, it doesn’t feel long. Each question is presented on its own page, with the answers laid out beneath in nice, simple boxes — often adorned with emojis.

Instead of seeing one long, time-consuming quiz, users are guided through a seemingly quick, easy set of questions. This is like a Sherpa taking you up Mount Everest without ever letting you see what’s ahead.

The result in Vitl’s case is a higher completion rate, which of course leads to higher sales.

Jakob's Law: The Power of Familiarity

Kiss the Hippo, like so many other e-commerce sites, lets users see their shopping cart before taking them to the checkout page

Jakob’s Law emphasises the importance of familiarity in UX design. Users expect digital interfaces to behave consistently with their prior experiences. When this isn’t case, it may cause confusion and ultimately detract from the website’s primary objective.

By following established design patterns/conventions (standard navigation menus, intuitive iconography, etc.) designers can leverage users’ existing mental models to aid usability and comprehension.

The ‘burger menu’ on the 1981 Xerox Star PC

Take the example of the burger menu: three horizontal lines stacked on top of one another, resembling the patty and buns of the hamburger. Originally designed by Norm Cox as part of the user interface for the Xerox Star PC, this icon design is now universally adopted to the point where people don’t even need to think about what the icon could mean.

Jakob’s Law can also be unique to specific sectors. E-commerce sites, for example, largely follow the same pattern as far as the customer journey is concerned:

1. Landing page

2. Product category page

3. Product detail page

4. Shopping cart page

5. Checkout page

6. Order confirmation page

Any deviation from this well-known path can confuse a potential customer and lead to an abandoned. When this happens en masse, the impact on sales can be drastic.

Miller's Law: Harnessing Cognitive Capacity

An accordion on D&Co International’s website, designed by Opignac

Miller’s Law posits that the average human can hold approximately seven (plus or minus two) items in their short-term memory at once.

For UX designers, therefore, it is important to break down large batches of information into smaller, more digestible chunks. By doing so, and with the use of visual aids such as lists, diagrams, and hierarchical structures, designers can prevent cognitive overload, helping users to digest content more easily.

A common tool for implementing Miller’s Law is the ‘accordion’, which uses a set of vertically stacked panels (resembling the bellows on the musical instrument) to hide detail-level information. This layout prevents cognitive overload, instead putting the user in charge of what is visible/relevant.

A comparison between how Apple and Huawei present their tablets in a thumbnail

No-one understands this law better than Apple, who put it front and centre of their design philosophy.

Look at how their iPad/table thumbnail differs to Huawei’s, for example, who not only have the product name, but the: tagline, company name, another product name(?), 3x product features, an upsell to a separate product, price, and a ‘Learn More’ button.

Is this all necessary when you’ll be presenting the information on the next page anyway? No is the answer.

Summary

Daniel Kahneman’s Thinking Fast and Slow (2011)

To summarise, we have explored four different laws here:

1. Fitt’s Law (make important things visually obvious)

2. Hick’s Law (don’t overload users with too many choices)

3. Jakob’s Law (stick to familiar design)

4. Miller’s Law (don’t overload users with too much information at once)

If you’d like to read further into the psychology behind these laws, we'd highly recommend Daniel Kahneman’s Thinking Fast and Slow — the go-to book on heuristics and System One / System Two thinking.