Understanding human behavior through UX/UI psychological principles is essential to designing intuitive digital experiences. By identifying how our brain processes and retains information, designers can make more informed decisions about visual hierarchy, navigation, and interaction.
In this article, I will introduce you to five UX/UI psychological principles keys that can improve your design process. Thus, each principle is illustrated with concrete examples, making it easier to apply them to your work.
1. Hick's Law: Less is more
Hick's Law states that the more options a user has, the longer it will take to make a decision.
Imagine you are in a restaurant. A 10-page menu will overwhelm you with options, while a single-page menu will make your choice easier. The same phenomenon applies to digital interfaces.
For example, a cluttered navigation bar can make finding information complex and frustrating. That’s why most navigation menus display only a few main categories, with subcategories accessible by hovering or clicking. Similarly, e-commerce sites use carousels to display a limited number of products at a time, avoiding cognitive overload while still providing choice.
How to apply it?
- Simplify navigation by grouping content into clear categories.
- Limit the number of options visible in menus and filters.
Hick's Law is widely used in UX to simplify navigation and speed up decision making, as explained in Nielsen Norman Group.
2. Cognitive Load: Don’t overload the user
Cognitive load refers to the mental effort required to process information. The higher the effort, the more likely the user is to become frustrated or drop out.
There are three types of cognitive load:
- Intrinsic charge : The effort required to understand new information. For example, a tourist trying to decipher a Paris metro map for the first time will have difficulty understanding the interweaving of lines, colors, and stations.
- German charge : The effort of processing information and integrating it into long-term memory. That is why the use of familiar patterns (hamburger menus, tab bars) allows users to quickly adapt to a new interface.
- Extrinsic load : The wasted effort caused by poor design. A web page with multiple fonts, excessive colors, and a confusing hierarchy of information distracts and complicates navigation.
How to apply it?
- Use known interface patterns to reduce learning effort.
- Define a clear visual hierarchy with well-defined typography, spacing, and colors.
- Avoid unnecessary distractions by keeping interfaces clean and functional.
Reducing cognitive load is essential to improving user experience, as detailed in this article from theInteraction Design Foundation.
3. The Von Restorff Effect: The Power of Contrast
The Von Restorff Effect suggests that elements that stand out are easier to remember.
Imagine a group of nine boys and one girl: the girl will immediately catch your attention. This principle also applies to UX/UI. A call-to-action (CTA) button using a bright color will immediately stand out against a neutral background. This contrast can be created through color, size, shape, typography or even animation.
How to apply it?
- Make key actions (like “Sign Up” or “Buy Now”) visually distinct.
- Use contrast to highlight essential elements without overwhelming the design.
- Experiment with animations or micro-interactions to subtly guide attention.
4. The Serial Position Effect: Location Matters
The serial position effect explains that we remember the first and last items in a list better.
For example, during a play, the audience will remember the opening and closing scenes more than the middle ones. This principle directly influences the design of interfaces, particularly the location of navigation elements.
On mobile apps, essential actions like navigation are often placed at the top or bottom of the screen, ensuring their accessibility and memorization.
How to apply it?
- Prioritize key elements in navigation menus.
- Use strategic locations for banners, notifications and promotions.
5. Fitts' Law: Make Clicks Easy
Fitts' Law states that the time taken to reach a target depends on its size and the distance to be covered.
In UX, this means that the larger and closer an interactive element is, the easier it will be to click or tap. For example, a product card with an image and text should be fully clickable rather than limiting the interaction to a small “View Details” button.
How to apply it?
- Make sure buttons and interactive elements are large enough to be easily tapped on mobile.
- Provide sufficient spacing between interactive elements to avoid misclicks.
Conclusion
Applying psychology principles to UX/UI isn’t just about aesthetics – it’s about designing experiences that align with how users think and interact with digital. Here’s a recap of the five principles discussed:
- Hick's Law : Reduce choices to speed up decision making.
- Cognitive load : Reduce mental effort with a clear and intuitive design.
- Von Restorff Effect : Use contrast to highlight essential elements.
- Serial position effect : Place crucial information in strategic locations.
- Fitts' Law : Make interactive elements easier to access and use.
Of course, there are many other psychological principles that influence UX/UI, but by incorporating these five concepts into your work, you will create products that are more intuitive and appreciated by users.
Aki Matsunaga, UX/UI designer and Product designer at UX-Republic
