UX laws & heuristics.

how the eye groups what it sees, before anyone reads a word.

• Law of Proximity

  elements close to one another are perceived as a single group, more related than elements spaced farther apart.

  Gestalt principle

  in practice · use spacing to show what belongs together, before you reach for boxes or lines.

• Law of Similarity

  elements that share visual characteristics are perceived as related, even when they are separated.

  Gestalt principle

  in practice · style related items the same way so the eye connects them on its own.

• Law of Common Region

  elements inside a shared, clearly defined boundary are perceived as one group.

  Gestalt principle

  in practice · a card or panel groups content faster than closeness alone.

• Law of Uniform Connectedness

  elements that are visually tied together are perceived as more related than elements that are not.

  Gestalt principle

  in practice · a line, arrow, or shared strip is the loudest way to say two things belong together.

• Law of Prägnanzthe law of simplicity

  people interpret ambiguous or complex images in the simplest form available, because it takes the least effort to make sense of.

  Gestalt principle

  in practice · favor clean, regular shapes people can read at a glance.

people see less, and remember less, than we assume. design for that.

• Miller's Law

  the average person can hold about seven, plus or minus two, items in working memory at once.

  George Miller, 1956

  in practice · do not treat it as a hard rule. chunk content so it stays easy to process.

• Chunking

  grouping separate pieces of information into larger, meaningful units lets people hold and process more of it.

  George Miller

  in practice · break long numbers, lists, and text into chunks.

• Working Memory

  the limited system that briefly holds the information a person is actively using to think or act.

  cognitive psychology

  in practice · keep needed information on screen so users never memorize across steps.

• Cognitive Load

  the total amount of mental effort being used in working memory at a given moment.

  John Sweller

  in practice · cut needless choices, jargon, and steps so effort goes to the goal, not the interface.

• Selective Attention

  the mind focuses on a subset of the available information and filters the rest out.

  cognitive psychology

  in practice · anything that looks like an ad gets ignored. do not disguise key content as noise.

• Serial Position Effect

  people recall the first and last items in a series best, and the middle items least.

  Hermann Ebbinghaus

  in practice · put the most important actions and items at the start and the end.

• Von Restorff Effectthe isolation effect

  when several similar items are present, the one that differs is the most likely to be remembered.

  Hedwig von Restorff, 1933

  in practice · make the single most important action visually distinct.

• Peak-End Rule

  people judge an experience largely by how it felt at its most intense point and at its end, not by the average of every moment.

  Daniel Kahneman

  in practice · design a strong peak and a clean finish, not just a good average.

• Zeigarnik Effect

  people remember interrupted or unfinished tasks better than completed ones.

  Bluma Zeigarnik

  in practice · progress bars and checklists use that pull to draw people toward completion.

the gap between wanting to do something and actually doing it.

• Hick's Law

  the time to make a decision grows with the number and complexity of the choices available.

  Hick & Hyman

  in practice · reduce or stage choices to help people move.

• Fitts's Law

  the time to move to a target is a function of the target's distance and its size.

  Paul Fitts, 1954

  in practice · make important targets big and close. tiny, far buttons are slow and error-prone.

• Choice Overload

  too many options increase cognitive effort and can make people less likely to choose at all.

  Iyengar & Lepper

  in practice · curate, set smart defaults, and reveal detail progressively.

• Goal-Gradient Effect

  the tendency to move toward a goal speeds up as the goal gets closer.

  Clark Hull

  in practice · show progress and give a visible head start so the finish feels within reach.

• Flow

  a state of full immersion and focus that occurs when the challenge of a task matches a person's skill.

  Mihály Csíkszentmihályi

  in practice · match challenge to skill and remove interruptions to protect it.

• Paradox of the Active User

  people begin using software immediately without reading instructions, even though taking time to learn would help them.

  Carroll & Rosson

  in practice · design so they can succeed while diving straight in.

people arrive with expectations. meet them, or feel wrong.

• Aesthetic-Usability Effect

  people tend to perceive attractive designs as easier to use than less attractive ones.

  Kurosu & Kashimura, 1995

  in practice · polish earns trust, but it is not a substitute for real usability.

• Jakob's Law

  people spend most of their time on other products, so they expect yours to work the way those already do.

  Jakob Nielsen

  in practice · meet conventions before you decide to break them.

• Mental Model

  a person's internal picture of how something in the real world works.

  cognitive science

  in practice · match it, or the product feels broken even when it works.

• Cognitive Bias

  a systematic pattern of deviation from rational judgment that shapes the decisions people make.

  behavioral science

  in practice · know them so you can design honestly, not exploit them.

how the thing itself should be built and behave.

• Occam's Razor

  among solutions that work equally well, the one with the fewest assumptions tends to be the best.

  William of Ockham

  in practice · remove elements until removing one more would break it.

• Tesler's Lawconservation of complexity

  every system carries an amount of complexity that cannot be reduced, only shifted between the product and the user.

  Larry Tesler

  in practice · decide whether the system or the user carries it, and spare the user.

• Postel's Lawthe robustness principle

  “be conservative in what you do, be liberal in what you accept from others.”

  Jon Postel, RFC 761

  in practice · accept messy human input gracefully. respond in a clear, reliable way.

• Doherty Threshold

  productivity rises sharply when a system responds fast enough, under about 400 ms, that neither the person nor the computer waits on the other.

  Doherty & Thadani, 1982

  in practice · keep interactions fast, or cover latency with instant feedback.

• Parkinson's Law

  “work expands so as to fill the time available for its completion.”

  C. Northcote Parkinson, 1955

  in practice · clear limits help tasks finish. without them, scope bloats.

• Pareto Principlethe 80/20 rule

  for many outcomes, roughly 80 percent of the effects come from 20 percent of the causes.

  Vilfredo Pareto

  in practice · find the few things most users need and make those excellent.

the 1994 usability heuristics, still the fastest audit checklist in the discipline. published by the Nielsen Norman Group.

• 01Visibility of System Status

  always tell people what is happening. timely, honest feedback keeps them oriented.

  in practice · show loading states, progress, and confirmations. never leave a user guessing whether an action worked.

• 02Match Between the System and the Real World

  speak the user's language. use words and ideas they already know, in an order that makes sense.

  in practice · label things the way users would say them, not the way the database stores them.

• 03User Control and Freedom

  people make mistakes. offer clear exits, undo, and redo so they never feel trapped.

  in practice · put an obvious cancel, back, and undo on every risky step. mark the emergency exits.

• 04Consistency and Standards

  the same word or control should mean the same thing everywhere. follow platform conventions.

  in practice · reuse one component and one word for one job. a button that says publish always publishes.

• 05Error Prevention

  the best error message is the one that never appears. prevent slips, then confirm risky actions.

  in practice · disable impossible actions, lean on good defaults, and confirm the destructive ones before they happen.

• 06Recognition Rather Than Recall

  show options instead of making people remember them. recognizing beats recalling.

  in practice · surface recent items, hints, and visible options instead of empty fields to fill from memory.

• 07Flexibility and Efficiency of Use

  let newcomers take the simple path and experts take shortcuts, without either getting in the way.

  in practice · add shortcuts, saved views, and bulk actions power users find but beginners never trip over.

• 08Aesthetic and Minimalist Design

  keep only what serves the goal. every extra element competes with the ones that matter.

  in practice · cut anything that does not help the current task. whitespace is not wasted space.

• 09Help Users Recognize, Diagnose, and Recover From Errors

  say what went wrong and how to fix it, in plain language. no codes, no blame.

  in practice · write the error in plain words, point at the field, and offer the fix in one tap.

• 10Help and Documentation

  ideally none is needed, but when it is, make it easy to find and focused on the task.

  in practice · put help where the question is asked: inline hints, tooltips, and searchable docs, not a buried manual.