Laws of UX

A list of rules that UX designers should consider when designing user interfaces.

Heuristics

A heuristic is a simple, experience-based rule used to make decisions or solve problems quickly. In UX, it’s often applied to evaluate the usability of interfaces.

Aesthetic-Usability Effect

Users often perceive aesthetically pleasing design as design that’s more usable.

Fitts’s Law

The time to acquire a target is a function of the distance to and size of the target.

Goal Gradient Effect

People are more motivated to complete a task the closer they are to finishing it.

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.

Miller’s Law

The average person can only keep 7 (plus or minus 2) items in their working memory.

Paradox of the Active User

The more users engage with a site, the more they’ll be inclined to visit it again in the future.

Parkinson’s Law

Work expands so as to fill the time available for its completion.

Principles

Principles are high-level ideas that are used to inform the design of user interfaces.

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.

Occam’s Razor

Among competing hypotheses, the one with the fewest assumptions should be selected.

Pareto Principle

Roughly 80% of the effects come from 20% of the causes.

Postel’s Law

Be liberal in what you accept, and conservative in what you send.

Tesler’s Law

There is a certain amount of complexity which cannot be reduced.

Gestalt

Gestalt principles explain how humans perceive the world around them.

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.

Law of Similarity

The human eye tends to build a relationship between similar elements in a design.

Law of Uniform Connectedness

Elements that are visually connected are perceived as more related than elements with no connection.

Cognitive Bias

Cognitive biases are systematic patterns of deviation from norm or rationality in judgment.

Peak-End Rule

People judge an experience largely based on how they felt at its peak (i.e., its most intense point) and at its end, rather than based on the total sum or average of every moment of the experience.

Serial Position Effect

Users have a propensity to best remember the first and last items in a series.

Von Restorff Effect

The Von Restorff 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.