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Laws of UX

Based on both, the book with the same name written by Jon Yablonski, and the community’s top reference experts.

Jakob’s Law

Users spend most of their time on other sites. They would prefer (and expect) our site to work the same way other sites do. (Jakob Nielsen, 2000)

Users want to do, not to learn how to do. The best scenario is to have the opportunity to “use” other sites as the source of knowledge, where users experienced some friction because they had to learn, think, and adapt to it, while our site is the place where that knowledge just needs to be applied. It’s all about reducing the overall mental effort, lowering the cognitive load required to operate our site, so users are more likely to successfully achieve their goals.

When users enter a new site that is similar to other(s) they already know, they expect that new site to work the same way as the first one does because of the mental models they’ve built. Being familiar helps users feel comfortable. That’s why we should make use of well-known patterns, conventions, and standards to avoid unnecessary work.

One of the biggest challenges for designers is to align our own mental models with the ones of the users. To assume we do not know the users’ mental model is a good starting point. Ask, interview, and research not only about the users’ goals, but also about the users’ previous experiences and how that information can be applied to our own design.

Fitts’s Law

The time to acquire a target is a function of the distance to and size of the target. (Paul Morris Fitts, 1954)

Fitts’ law is a model for both predicting and measuring the interaction performance of humans on a given human-computer system.

To reduce the ratio of errors:

  1. Targets should be large enough.
  2. Targets should be at easy to find and acquire areas.
  3. Targets should be close to the current area of attention.
  4. Groups of targets should have ample space between them.

Hick’s Law

Miller’s Law

Postel’s Law

Peak-End Rule

Aesthetic-Usability Effect

Von Restorff Effect

Tesler’s Law

Dpherty Threshold

With Power Comes Responsibility

Applying Psychological Principles in Design

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