User experience (UX) is the most important aspect of any product. Well-designed UX drives user engagement. But badly designed UX doesn’t just cause app abandonment. It’s also been proven to damage your overall brand, making users less likely to engage with you in the future.

How can you avoid this? By considering the science and psychology behind your product’s UX and UI design.

What separates good and bad product design is understanding. Considering the motivations, goals and frustrations of your users gives you a deep understanding of how they’ll perceive and interact with your product.

The aesthetic-usability effect

UX design and psychology are closely related. There’s a great comparison from Joe Leech who likens a designer who doesn’t understand psychology to an architect who doesn’t understand physics. They’re that intertwined.

Aesthetics are, of course, an important element of any product design. But without an understanding of the social, behavioural and cognitive psychologies that drive your users’ decisions, great aesthetics can actually end up damaging your user experience.

Why? Because expectations are so much higher. It’s called the aesthetic-usability effect. People automatically assume that a great-looking product must be more intuitive. So, if it isn’t, users end up blaming themselves. This leads to frustration and, ultimately, app abandonment.

It’s principles like these that separate top-ranking apps from the rest of the market. They divide the internal apps that engage employees from the ones that alienate them.

In this article, I’ll break down five psychological principles you need to consider in your product design to delight users and ensure a return on your investment.

1. Keep choices simple

There’s a reason why it takes you longer to pick from a restaurant menu with 100 different options. It’s called Hick’s Law. The more choices you offer users, the longer it’ll take them to arrive at a decision.

Hick’s Law plays a fundamental role in how we approach digital product design. When you’re trying to help your user achieve a goal or solve a challenge, speed is paramount. The more elements you show them, the longer it’ll take for them to achieve their goal and the more frustrated they’ll become.

Instead of offering users every possible option at once, the design should prioritise the key elements. Choices should be limited to as few as possible and long, complicated processes need to be broken down into simpler steps.

Meanwhile, less common in-app actions need to be grouped together under menus or clearly defined sub-category sections. And any unnecessary items should, of course, be removed completely.

All of this reduces the amount of time it takes for users to arrive at a decision, helping them achieve their goal faster with less friction.

2. Make important actions easy to reach

The further away your thumb or mouse is from the element you want to interact with, and the smaller that element is, the longer it takes to complete the action. This is called Fitts’ Law and it’s a fundamental principle of good UI design.

The longer an interaction takes, the higher the chance that users give up. To combat this, every interactable element should be big enough for users to know what it is and to select it with ease.

The highest accuracy for buttons, for example, is between 42 and 72 pixels wide. So making high-priority, frequently used actions 72 pixels allows users to hit their target even when their finger or cursor is slightly off.

The final component of Fitts’ Law is distance. In the era of super-sized screens, this is becoming increasingly important. Stretching to reach a hamburger menu in the top left hand of my S10+ screen feels like fighting someone in a thumb war.

That’s why, at Sonin, we wireframe with reachability heatmaps. This way, we’re able to ensure that all the most important components and common actions are in the most easy-to-reach places. This lets users achieve their desired outcome much, much faster.

3. Prioritise positioning

Take a look at the list of words below. If I gave you a few minutes to memorise as many as you could, how would you fare?

  • Emphasis
  • Medicine
  • Prosper
  • Climb
  • Theft
  • Retailer
  • Warn
  • Captivate
  • Integration
  • Background
  • Potential
  • Order
  • Lost
  • Art
  • Party

When presented with this challenge, most people will have trouble recalling any of the words from the middle. But they often have a much easier time remembering words that are either early on in the list or towards the end.

Why? Because of the serial position effect which we can use to improve our digital product design. Take the navigation bar, for example. There’s a reason why Home is almost always on the far left. And it’s the same reason why the far-right is commonly reserved for profiles or inboxes.

Putting your most important items in the easiest-to-remember positions will limit the amount of recall required from users. By considering the serial position effect, you’ll be able to make your product more intuitive and your users more adept.

4. Be wary of selective disregard

Today, we’re all experienced products users. And with that experience comes learnings that shape the way we interact with products. In the digital world, there are few learnings more important than the ability to ignore irrelevant information.

It’s impossible for users to give attention to every single digital stimulus that they see. So instead, they use selective attention to pinpoint what’s important. We call this phenomenon selective disregard. And it’s the reason that you’re more likely to get hit by lightning 237 times than you are to click on a banner advert.

But selective disregard doesn’t just apply to advertising. If an element isn’t clearly related to their task, users will ignore it without even thinking. Every element should be designed with selective disregard and users’ expectations in mind to ensure ease-of-use.

5. Finally, don’t be evil

In recent years, and after a fair amount of backlash, LinkedIn has updated its on-boarding but beforehand it was one company notorious for employing dark patterns. This is a practice where companies carefully craft a user interface with the intention of tricking users into doing things they didn’t mean to.

The technique is often used to trick people into buying unnecessary insurance for their purchases or unwittingly signing up for recurring subscriptions.

To do this, dark patterns often take advantage of the built-in expectations we all have as users. Brightly coloured buttons mean positive confirmation. A right-facing arrow means moving forward. Left takes you back.


Wrong. Dark patterns pray upon these expectations and play on people’s fears. They prioritise business goals over users. Every business has desired outcomes they want to achieve through their product. But there are ways of achieving them without damaging the trust people have in your brand.

Begin by pinpointing the opportunities where you can provide real value for your users. Once you’ve done this, you can find where your users’ goals intersect with your business strategies. This approach ensures your product design provides value for everyone involved.

Three dark patterns used by brands and why they should be avoided

Final thoughts

The psychology principles we’ve covered here impact how users interact with your product from before they even launch it. They’re also present all the way through the discovery and decision process. It’s clear then that none of these principles should be an afterthought. They have to be carefully considered and thoroughly researched before you even begin the build.

Accounting for the psychology of your users during product design ensures that their experience is frictionless from the first time they launch your app. With just a couple of screens to delight your users, understanding their psychology will reduce abandonment and drive engagement across-the-board.