Psychology plays a central role in UX design because products are built for humans, and the Human Factor must always take priority.
Human factors describe the range of variables that people bring to a product.
Common Human Factors that inform design
- Impatience
- Limited memory
- Needing analogies
- Limited concentration
- Changes in need
- Needing motivation
- Prejudices
- Fears
- Making errors
- Misjudgment
Psychological models to help design for human factors
- Mental Models – internal maps users rely on to predict behavior
- Feedback Loops – outcomes users perceive at the end of a process
Psychology principles that influence design
Principles captured from Jon Yablonski and his Laws of UX.
Heuristic
- Aesthetic-Usability Effect – attractive designs feel easier to use
- Fitts' Law – speed depends on target size and distance
- Goal Gradient Effect – motivation rises as users near completion
- Hick's Law – more choices = slower decisions
- Jakob's Law – users expect familiarity across sites
- Miller's Law – working memory holds about 7 ± 2 items
- Parkinson's Law – tasks expand to fill available time
Principle
- Doherty Threshold – interaction feels smooth under 400ms response
- Occam's Razor – the simplest valid solution is best
- Pareto Principle – 80% of results often come from 20% of causes
- Postel's Law – accept broadly, output conservatively
- Tesler's Law – complexity cannot be removed, only shifted
Gestalt Principles
Gestalt = “shape” (German). Explains how humans group, pattern, and simplify perception.
- Law of Common Region – shared boundaries group elements
- Law of Proximity – nearby objects are seen as related
- Law of Prägnanz – people choose the simplest interpretation
- Law of Similarity – similar elements are seen as a whole
- Law of Uniform Connectedness – connected items feel more related
See also: User Testing article, UX Collective article
Cognitive Bias
- Peak-End Rule – memory is shaped by peaks and endings
- Serial Position Effect – first and last items remembered best
- Von Restorff Effect – distinct items stand out and are recalled
- Zeigarnik Effect – unfinished tasks stick in memory
Significance of Psychology in UX Design
It is pretty imperative that psychology plays a major role in UX design and must consider the human factor above everything else. The term Human Factor describes the range of variables that humans bring to the product.
Common Human Factors that inform design
- Impatience
- Limited memory
- Needing analogies
- Limited concentration
- Changes in need
- Needing motivation
- Prejudices
- Fears
- Making errors
- Misjudgment
Psychological models to help design for human factors
- Mental Models - Mental models are internal maps that allow humans to predict how something will work.
- Feedback Loops - The outcome a user gets at the end of a process.
Psychology principles that influence design
The following principles are captured from Jon Yablonksi's work on Laws of UX. To learn more read the book Laws of UX
Heuristic
- Aesthetic-Usability Effect - Users often perceive aesthetically pleasing design as design that's more usable.
- Fitts' Law - The time to acquire a target is a function of distance to and the size of the target.
- Goal Gradient Effect - The tendency to approach a goal increases with proximity to the goal.
- Hick's Law - The time taken to make a decision increases with the number and complexity of choices.
- Jakob's Law - Users spend most of the time on other sites and thus expect your site to work the same.
- Miller's Law - An average person can keep only 7 (plus or minus 2 items) in their working memory.
- Parkinson's Law - Any task will inflate until all of the available time is spent. ^parkinsons-Law
Principle 8. Doherty Threshold - Productivity soars when a computer and its users interact at a pace of (<400ms) that ensures that neither has to wait on the other. 9. Occam's Razor - Among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected. 10. Pareto Principle - For many events roughly 80% of the results come from 20% of the causes. 11. Postel's Law - Be liberal in what you accept and conservative in what you send. 12. Tesler's Law - Also known as the law of conservation of complexity, it states that for any system there is a certain amount of complexity that cannot be reduced.
Gestalt Principles Gestalt principles state how humans group similar elements, recognize patterns, and simplify complex images when we perceive objects. the word gestalt is of German origin and it means shape.
- 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 the 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.
- Law of Uniform Connectedness - Elements that are visually connected are perceived as more related than elements with no connection.
Learn more about Gestalt Principles, through this article from User Testing that describes additional Gestalt Principles and this article from UX Collective with examples of the Gestalt Principles in wireframes.
Cognitive Bias 18. Peak-End Rule - People judge an experience largely based on how they felt at its peak and its end, rather than the sum or average of every moment of the experience. 19. Serial Position Effect - Users have a propensity to remember the first and last items in a series. 20. Von Restorff Effect - Also known as the Isolation Effect. it predicts that when multiple similar objects are present, the one that differs from the rest is most likely to be remembered. 21. Zeigarnik Effect - People remember uncompleted or interrupted tasks better than completed tasks.