Laws of UX Defintions

Aesthetic-Usability Effect

Users often perceive aesthetically pleasing design that's more usable.

Doherty Threshold

Productivity soars when a computer and its users interact at a pace (

Fitts's Law

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

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 Pragnanz

People will perceive and interpret ambiguous or complex images as the simplest form(s) possible, because it is the interpretation that requires the least cognitive effort for us.

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.

Miller's Law

The average person can only keep 7 (plus of 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.

Pareto Principle

States that, 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 peak and at its end, rather than the total sum or average of every moment of the experience.

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.

Tesler's Law/Law of Conservation of Complexity

States that for any system there is a certain amount of complexity which cannot be reduced.

Von Restorff Effect/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.