Laws of UX is a collection of best practices that designers can consider when building user interfaces.
The updated Laws of UX large format index poster is now available! Additions include Paradox of the Active User, Selective Attention, Cognitive Bias, and more. Check it out →
Aesthetic-Usability Effect
Users often perceive aesthetically pleasing design as design that's more usable.
Choice Overload
The tendency for people to get overwhelmed when presented with a large number of options, often used interchangeably with the term paradox of choice.
Chunking
A process by which individual pieces of an information set are broken down and then grouped together in a meaningful whole.
Cognitive Bias
A systematic error of thinking or rationality in judgment that influences our perception of the world and our decision-making ability.
Cognitive Load
The amount of mental resources needed to understand and interact with an interface.
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.
Fitts's Law
The time to acquire a target is a function of the distance to and size of the target.
Flow
The mental state in which a person is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity.
Goal-Gradient Effect
The tendency to approach a goal increases with proximity to the goal.
Hick's Law
The time it takes to make a decision increases with the number and complexity of choices.
Jakob'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.
Law of Common Region
Elements tend to be perceived into groups if they are sharing an area with a clearly defined boundary.
Law of Proximity
Objects that are near, or proximate, to each other tend to be grouped together.
Law of Prägnanz
People will perceive and interpret ambiguous or complex images as the simplest form possible, because it is the interpretation that requires the least cognitive effort.
Law of Similarity
The human eye tends to perceive similar elements in a design as a complete picture, shape, or group, even if those elements are separated.
Law of Uniform Connectedness
Elements that are visually connected are perceived as more related than elements with no connection.
Mental Model
Users have a pre-existing mental model of how things work. Designs that align with those models feel intuitive; designs that conflict with them cause confusion.
Miller's Law
The average person can only keep 7 (plus or minus 2) items in their working memory.
Occam's Razor
Among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected.
Paradox of the Active User
Users never read manuals but start using the software immediately. They make up an explanation for what they see and assume the interface will reflect their mental model.
Pareto Principle
For many events, roughly 80% of the effects come from 20% of the causes.
Parkinson's Law
Any task will inflate until all of the available time is spent.
Peak-End Rule
People judge an experience largely based on how they felt at its most intense point and at its end, rather than based on the sum or average of every moment.
Postel's Law
Be liberal in what you accept, and conservative in what you send.
Serial Position Effect
Users have a propensity to best remember the first and last items in a series.
Selective Attention
Our experience of the world is filtered through what we choose to attend to, and the resources available to do so.
Tesler's Law
Also known as The Law of Conservation of Complexity, for any system there is a certain amount of complexity that cannot be reduced.
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.
Zeigarnik Effect
People remember uncompleted or interrupted tasks better than completed tasks.