Laws of UX
Using Psychology to Design Better Products & Services
by Jon Yablonski
Laws of UX: Using Psychology to Design Better Products & Services by Jon Yablonski is a great starting point for anyone new to UX design or if you’re curious about how psychology can help you create better user experiences. The book takes complex psychological principles and makes them easy to understand, showing how they can be applied to design in practical ways. In this blog, I’ll summarise the key insights, along with examples of how you can use these principles in your own designs.
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Designing with human nature in mind
Humans have some hard-wired ways of perceiving and processing the world around us. When we design products that go against these natural tendencies, we’re basically making things harder for users. It's like asking people to fight their instincts. Understanding how our brains work can help us create designs that feel intuitive, allowing users to interact with products without frustration.
Where do the Laws of UX come from?
The Laws of UX come from well-established principles in psychology, behavioral science, human-computer interaction, and design. Although Jon Yablonski brought them together for UX designers, these laws are built on decades of research and practice. They reflect how we think, behave, and interact with the world, providing guidance to create user-friendly designs.
Key Insights from Laws of UX
Jacob's Law
Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know.
Takeaways
1.
Users will transfer expectations they have built around one familiar product to another that appears similar.
2.
By leveraging existing mental models, we can create superior user experiences in which the users can focus on their tasks rather than on learning new models.
3.
When making changes, minimize discord by empowering users to continue using a familiar version for a limited time.
“…the less mental energy users have to spend learning an interface, the more they can dedicate to achieving their objectives”
“Users prefer your site or app to work the way they are accustomed to. Designing with familiarity reduces the learning curve and increases usability.”
“…always begin with common patterns and conventions, and only depart from them when makes sense to. If you can make a compelling argument for making something different to improve the core user experience, that’s a good sign that it’s worth exploring. If you go the unconventional route, be sure to test your design with users to ensure they understand how it works.”
Fitt’s Law
The time to acquire a target is a function of the distance to and size of the target.
Takeaways
1.
Touch targets should be large enough for users to accurately select them.
2.
Touch targets should have ample spacing between them.
3.
Touch targets should be placed in areas of an interface that allow them to be easily acquired.
“…people prefer to view and touch the center of the smartphone screen, and this is where accuracy is the highest. They also tend to focus on the center of the screen, as opposed to scanning from the upper left to the lower right as is common on desktop devices.”
“Form submission buttons are usually positioned in close proximity to the last form input, because buttons that are intended to complete an action (filling out a form) should be close to the active element. This positioning not only ensures that the two types of input are visually related but also ensures that the distance the user must travel from the last form input to the submission button is minimal.”
Hick’s Law
Users often perceive aesthetically pleasing design as design that’s more usable.
Takeaways
1.
Minimize choices when response times are critical to increase decision time.
2.
Break complex tasks into smaller steps in order to decrease cognitive load.
3.
Avoid overwhelming users by highlighting recommended options.
4.
Use progressive onboarding to minimize cognitive load for new users.
5.
Be careful not to simplify to the point of abstraction.
“…the time it takes to make a decision increases with the number and complexity of choices available.”
“…studies have shown that simply adding text labels to accompany icons will provide clarity and aid users with both discovery and recognition. This practice is even more critical when using icons for important elements such as navigation.”
Miller’s Law
The average person can only keep 7 (plus or minus 2) items in their working memory.
Takeaways
1.
Don’t use the “magical number seven” to justify unnecessary design limitations.
2.
Organize content into smaller chunks to help users process, understand, and memorize easily.
3.
Remember that short-term memory capacity will vary per individual, based on their prior knowledge and situational context.
"...when the amount of information coming in exceeds the space we have available, we struggle mentally to keep up - tasks become more difficult, details are missed, and we begin to feel overwhelmed."
“When we chunk content in design, we are effectively making it easier to comprehend. Users can then scan the content, identify the information that aligns with their goal(s), and consume that information to achieve their goal(s) more quickly. By structuring content into visually distinct groups with a clear hierarchy, we can align the information we present with how people evaluate and process digital content.”
Postel’s Law
Be liberal in what you accept, and conservative in what you send.
Takeaways
1.
Be empathetic to, flexible about, and tolerant of any of the various actions the user could take or any input they might provide.
2.
Anticipate virtually anything in terms of input, access, and capability while providing a reliable and accessible interface.
3.
The more we can anticipate and plan for in design, the more resilient the design will be.
4.
Accept variable input from users, translating that input to meet your requirements, defining boundaries for input, and providing clear feedback to the user.
"Postel's law can help us bridge the gap between human and machine.”
“The first half of Postel’s law states that you should “be conservative in what you do”. In the context of design this can be interpreted as stipulating that the output of our efforts, whether that’s an interface or a comprehensive system, should be reliable and accessible. …”
“The second half of the principle states that you should “be liberal in what you accept from others”. In the context of design, this can be taken to mean the acceptance of input from users via any input mechanism and in a variety of possible formats. It applies to data entered into a form via mouse and keyboard, assistive technology, touch and gesture input from mobile users,…”
Peak-End Rule
People judge an experience largely based on how they felt at its peak and at its end, rather than the total sum or average of every moment of the experience.
Takeaways
1.
Pay close attention to the most intense points and the final moments (the “end”) of the user journey.
2.
Identify the moments when your product is most helpful, valuable, or entertaining and design to delight the end user.
3.
Remember that people recall negative experiences more vividly than positive ones.
"...judging the experience positively because of the less painful end."
"...Uber realized that waiting was an unavoidable part of its business model and sought to reduce this pain point by focusing on three concepts related to wait time: idleness aversion, operational transparency, and the goal gradient effect. Uber express pool customers are presented with an animation that help to keep them not only informed but also entertained (idleness aversion)."
Aesthetic-Usability Effect
Users often perceive aesthetically pleasing design as design that’s more usable.
Takeaways
1.
An aesthetically pleasing design creates a positive response in people’s brains and leads them to believe the design actually works better.
2.
People are more tolerant of minor usability issues when the design of a product or service is aesthetically pleasing.
3.
Visually pleasing design can mask usability problems and prevent issues from being discovered during usability testing.
"Contrary to what we've been thought not to do, people in fact judge books by their cover. This isn't actually a bad thing, though - in fact, it's necessary. Automatic cognitive processing is helpful because it enables us to react quickly."
"Aesthetically pleasing design can influence usability by creating a positive emotional response, which in turn enchances people's cognitive abilities."
Von Restorff Effect
The Von Restorff effect, also known as The Isolation Effect, predicts that when multiple similar objects are present, the one that differs from the rest is most likely to be remembered.
Takeaways
1.
Make important information or key actions visually distinctive.
2.
Use restraint when placing emphasis on visual elements to avoid them competing with one another and to ensure salient items don’t get mistakenly identified as ads.
3.
Don’t exclude those with a color vision deficiency or low vision by relying exclusively on color to communicate contrast.
4.
Carefully consider users with motion sensitivity when using motion to communicate contrast.
“Related to banner blindness is change blindness, which describes the tendency for people to fail to notice significant changes when they lack strong enough visual cues, or when their attention is focused elsewhere. Since our attention is a limited resource, we often ignore information we deem irrelevant in order to complete tasks efficiently.”
“Color, scale, shape, negative space, and motion are additional properties that can make specific elements or content stand out in comparison to adjacent information.”
Tesler’s Law
Tesler’s Law, also known as The Law of Conservation of Complexity, states that for any system there is a certain amount of complexity which cannot be reduced.
Takeaways
1.
All processes have a core of complexity that cannot be designed away and therefore must be assumed by either the system or the user.
2.
Ensure as much as possible of the burden is lifted from users by dealing with inherent complexity during design and development.
3.
Take care not to simplify interfaces to the point of abstraction.
"...Gmail now leverages artificial intelligence (AI) within your emails through a feature called Smart Compose. This intelligent feature can scan what you've typed and use that content to suggest words and phrases to finish your sentences, thus saving you additional typing and time."
Doherty Threshold
Productivity soars when a computer and its users interact at a pace (<400ms) that ensures that neither has to wait on the other.
Takeaways
1.
Provide system feedback within 400 ms in order to keep users’ attention and increase productivity.
2.
Use perceived performance to improve response time and reduce the perception of waiting.
3.
Animation is one way to visually engage people while loading or processing is happening in the background.
4.
Progress bars help make wait times tolerable, regardless of their accuracy.
5.
Purposefully adding a delay to a process can actually increase its perceived value and instill a sense of trust, even when the process itself actually takes much less time.
“Emotions can quickly turn to frustration and leave a negative lasting impact when users who are trying to achieve a task are met with slow processing, lack of feedback, or excessive load times.”
“While a 100ms response feels instantaneous, a delay of between 100 and 300 ms begins to be perceptible to the human eye, and people begin to feel less in control. Once the delay extends past 1000ms (1 sec), people begin thinking about other things; their attention wanders, and information important to performing their task begins to get lost, leading to an inevitable reduction in performance.”
Conclusion
Laws of UX by Jon Yablonski is a great resource for anyone looking to use psychology to create more intuitive, human-centered products and experiences. Personally, I found it to be an easy and insightful read. While I was familiar with many of the concepts, I appreciated how the author effectively bridged psychology and design, offering clear summaries of key principles. It also reminded me to reflect on my own design habits—like creating smaller buttons for aesthetic reasons—and shift toward more user-centered choices, such as using larger buttons aligned with Fitts' Law and WCAG guidelines. Whether you're new to UX or seeking to refine your skills, this book is a valuable guide to understanding design fundamentals.