UX Laws and Psychology Concepts

The Principle of Least Effort

People will take the path or action requiring the least amount of mental and physical energy to complete a task.

Paradox of the Active User

Users never read manuals but start using the software immediately.

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.

Tesler's Law

For any system there is a certain amount of complexity which cannot be reduced.

Hick's Law

The time it takes to make a decision increases as the number of alternatives increases

Stroop Effect

The mental dissonance caused when we attempt to make sense of two conflicting attributes at once.

Law of Pragnanz

People will perceive and interpret ambiguous or complex images as the simplest form(s) possible

Law of Closure

The tendency to fill in the gaps in an incomplete image.

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.

Occam's Razor

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

Postel's Law

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

Aesthetic-Usability Effect

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

Law of Uniform Connectedness

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

Law of Proximity

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

Law of Continuity

Elements arranged on a line or curve are perceived to be more related than elements not on the line or curve.

Law of Common Region

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

Simon Effect

Reaction times are usually faster and more accurate when the stimulus occurs in the same relative location as the response.

Fitt's Law

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

Accot-Zhai Steering Law

The time necessary to guide a pointer of drag a finger along a path that has no borders.

Serial Position Effect

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

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.

Von Restorff Effect

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

Pareto Principle

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

Campbell's Law

The more important a metric is in social decision making, the more likely it is to be manipulated.

Miller's Law

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

Goal-Gradient Effect

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

Parkinson's Law

Any task will expand to fill the available time.

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.

Bock's Constant

People just don't read. Honestly, they really don't!

Mental Model

An explanation of someone's thought process about how something works in the real world

Signifier

Clues in different forms that communicate what action is to be done within a system.

Short-Term Memory

The capacity to store a small amount of information in mind and keep it readily available for a short period of time.

Selective Attention

The process of focusing our attention only to a subset of the stimuli in the environment - usually those related to our goals

Cognitive Load

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

Mapping

The relationship between the elements of two sets of things

Cognitive Dissonance

When a user is confronted with an interface or affordance that appears to be intuitive but delivers unexpected results.

Analysis Paralysis

The inability to make a decision due to overthinking a problem.

Chunking

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

Contextual Inquiry

A field study that involves in-depth observation and interviews of a small sample of users to gain a robust understanding of work practices and behaviors.

Cognitive Load

When the amount of information coming in exceeds the space we have available, we struggle to mentally keep up - tasks become more difficult, details are missed, and we begin to feel overwhelmed.

Flow

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

Cognitive Bias

Systematic errors of thinking or rationality in judgement that influence our perception of the world and our decision-making ability.

Constraints

Physical, semantic, cultural, and logical constraints guide our actions and aid in interpretation.

Discoverability

The ability to discover what a system does, how it works, and what operations are possible

Affordances

Define what actions are possible with an object or interface based on the capabilities of the user.

Feedback

System responses that makes it clear to the user what action has been taken and what has been accomplished.

Conceptual Moden

An explanation, usually highly simplified, of how something works, which is formed through experience, training, and instruction.

Design Principles

An agreed-upon set of guidelines help frame how a design team approaches and solves problems