• 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.

  • 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 of 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.

  • Mental Model

    A compressed model based on what we think we know about a system and how it works.

  • 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.

  • Pareto Principle

    The Pareto principle states that, for many events, roughly 80% of the effects come from 20% of the causes.

  • 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.

  • Selective Attention

    The process of focusing our attention only to a subset of stimuli in an environment — usually those related to our goals.

  • 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.

  • 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.

  • Zeigarnik Effect

    People remember uncompleted or interrupted tasks better than completed tasks.