Objects that are near, or proximate to each other, tend to be grouped together.

The human eye tends to perceive similar elements as a complete picture, shape, or group, even if those elements are separated.

Elements tend to be perceived into groups if they are sharing an area with a clearly defined boundary.

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

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.

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

When multiple similar objects are present, the one that differs from the rest is most likely to be remembered.

A cognitive system that temporarily holds and manipulates information needed to complete tasks.

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

The amount of mental resources needed to understand and interact with an interface.

A process by which individual pieces of an information set are broken down and then grouped together in a meaningful whole.

A systematic error of thinking or rationality in judgment that influence our perception of the world and our decision-making ability.

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

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

People remember uncompleted or interrupted tasks better than completed tasks.

The time it takes to make a decision increases with the number and complexity of choices.

The tendency for people to get overwhelmed when they are presented with a large number of options, often used interchangeably with the term paradox of choice.

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

The tendency to approach a goal increases with proximity to the goal.

Productivity soars when a computer and its users interact at a pace (<400ms) that ensures that neither has to wait on the other.

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

Among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected.

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.

Any task will inflate until all of the available time is spent.

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

Users never read manuals but start using the software immediately.

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.

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

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.

The mental state in which a person performing some activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity.