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The laws of UX, tested on you

30 laws of how people think, grouped into five families. Open any one to read it in full.

All laws

30 laws · 5 families

Decision

5 laws
  • Hick's Law

    The more choices people see, the longer they take to decide.

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  • Jakob's Law

    People expect your site to work like the sites they already use.

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  • Occam's Razor

    When two designs work equally well, the simpler one wins.

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  • Choice Overload

    Show too many options and people pick nothing at all.

    Read the law
  • Pareto Principle

    Around 80% of the results come from 20% of the features.

    Read the law

Effort

5 laws
  • Fitts's Law

    Big, close targets are quick to tap. Small, far ones are slow.

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  • Doherty Threshold

    Respond in under 400ms and people stay engaged. Slower, and their mind drifts.

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  • Tesler's Law

    Every product has complexity. Someone has to handle it — the user or the system.

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  • Postel's Law

    Accept messy input from people. Give back clean, predictable output.

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  • Cognitive Load

    Every extra thing on screen uses up a bit of the user's mental energy.

    Read the law

Memory

6 laws
  • Miller's Law

    People can hold only about seven things in their head at once.

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  • Serial Position Effect

    People remember the first and last items in a list best.

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  • Von Restorff Effect

    The item that looks different is the one people remember.

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  • Peak-End Rule

    People judge an experience by its strongest moment and its ending, not the average.

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  • Zeigarnik Effect

    People remember unfinished tasks better than finished ones.

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  • Chunking

    Break information into small groups and it becomes easy to remember.

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Perception

11 laws
  • Aesthetic-Usability Effect

    Designs that look good feel easier to use, even when they are not.

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  • Law of Proximity

    Things placed close together look like they belong together.

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  • Law of Similarity

    Things that look alike seem related, even when they are far apart.

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  • Law of Common Region

    Items inside the same border are seen as one group.

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  • Law of Prägnanz

    People see the simplest possible shape, even in a complex image.

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  • Uniform Connectedness

    A line connecting two things groups them more strongly than colour or spacing.

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  • Selective Attention

    When people focus on one task, they stop seeing everything else.

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  • Law of Continuity

    The eye follows smooth paths. Lines that flow together are seen as one.

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  • Law of Closure

    People see complete shapes, even when parts are missing.

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  • Figure-Ground

    People split every scene into a subject and a background.

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  • Law of Symmetry

    Mirrored elements are seen as belonging together, as pairs.

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Behaviour

3 laws
  • Goal-Gradient Effect

    The closer people feel to a goal, the harder they push to finish it.

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  • Parkinson's Law

    A task stretches to fill however much time you give it.

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  • Paradox of the Active User

    People start using products right away. They do not read instructions first.

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Back to laws

The open library

45 interactive entries — the heuristics, biases, nudges and AI phenomena behind everyday decisions. Open any one to read it and see the demo.

All entries

45 entries · 4 shelves

Heuristics

8 entries
  • Heuristics 01 / 45

    Availability Heuristic

    Availability heuristic explains why easily recalled information feels more likely.

    Explore
  • Heuristics 02 / 45

    Recognition Heuristic

    Recognition can become a decision shortcut.

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  • Heuristics 03 / 45

    Scarcity Heuristic

    Limited availability can increase perceived value.

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  • Heuristics 04 / 45

    Affect Heuristic

    Emotions influence perceived risks and benefits.

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  • Heuristics 05 / 45

    Representativeness Heuristic

    Similarity can override statistical reasoning.

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  • Heuristics 06 / 45

    Fluency Heuristic

    Ease of processing influences judgment.

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  • Heuristics 07 / 45

    Familiarity Heuristic

    Familiarity influences preference.

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  • Heuristics 08 / 45

    Social Proof Heuristic

    People use others' behavior as evidence.

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Biases

20 entries
  • Biases 09 / 45

    Confirmation Bias

    People naturally seek information that supports existing beliefs.

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  • Biases 10 / 45

    Anchoring Bias

    The first piece of information strongly influences later judgments.

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  • Biases 11 / 45

    Loss Aversion

    Losses feel psychologically stronger than equivalent gains.

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  • Biases 12 / 45

    Decoy Effect

    An inferior option changes preferences between other choices.

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  • Biases 13 / 45

    Status Quo Bias

    People prefer familiar situations over uncertain alternatives.

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  • Biases 14 / 45

    Choice Overload

    Too many choices increase cognitive load.

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  • Biases 15 / 45

    Framing Effect

    The presentation of information changes decisions.

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  • Biases 16 / 45

    Endowment Effect

    Ownership creates emotional attachment.

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  • Biases 17 / 45

    Planning Fallacy

    People underestimate time and obstacles.

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  • Biases 18 / 45

    Sunk Cost Fallacy

    Past investment influences current decisions.

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  • Biases 19 / 45

    Availability Cascade

    Frequency can be mistaken for accuracy.

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  • Biases 20 / 45

    Dunning-Kruger Effect

    Limited knowledge can hide awareness of limitations.

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  • Biases 21 / 45

    Optimism Bias

    People naturally expect better outcomes for themselves.

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  • Biases 22 / 45

    Negativity Bias

    Negative information receives stronger attention.

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  • Biases 23 / 45

    Recency Bias

    Recent information is easier to recall.

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  • Biases 24 / 45

    Survivorship Bias

    Missing data creates incorrect conclusions.

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  • Biases 25 / 45

    Authority Bias

    Authority signals influence acceptance.

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  • Biases 26 / 45

    Halo Effect

    One positive trait influences unrelated judgments.

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  • Biases 27 / 45

    Mere Exposure Effect

    Familiar things feel safer.

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  • Biases 28 / 45

    IKEA Effect

    Effort increases emotional attachment.

    Explore

Nudges

9 entries
  • Nudges 29 / 45

    Default Nudge

    Defaults reduce effort and strongly influence decisions.

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  • Nudges 30 / 45

    Positive Framing Nudge

    Positive framing can increase acceptance and motivation.

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  • Nudges 31 / 45

    Social Norm Nudge

    Humans are influenced by perceived social expectations.

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  • Nudges 32 / 45

    High-Touch Outreach Nudge

    Human connection can increase engagement.

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  • Nudges 33 / 45

    Commitment Nudge

    Commitments create psychological pressure to stay consistent.

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  • Nudges 34 / 45

    Reminder Nudge

    Simple prompts help people overcome forgetfulness.

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  • Nudges 35 / 45

    Simplification Nudge

    Reducing complexity makes desired actions easier.

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  • Nudges 36 / 45

    Feedback Nudge

    Feedback helps people understand performance and progress.

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  • Nudges 37 / 45

    Choice Architecture Nudge

    The structure of choices influences decisions without removing freedom.

    Explore

AI phenomena

8 entries
  • AI phenomena 38 / 45

    Automation Bias

    People may over-trust automated systems and fail to verify recommendations.

    Explore
  • AI phenomena 39 / 45

    AI Sycophancy

    AI systems may optimize for satisfaction rather than accuracy.

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  • AI phenomena 40 / 45

    Anthropomorphism Effect

    Humans naturally assign human qualities to non-human systems.

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  • AI phenomena 41 / 45

    Calibration Failure

    Confidence scores can fail to represent true reliability.

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  • AI phenomena 42 / 45

    Automation Complacency

    Repeated automation success can reduce human attention.

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  • AI phenomena 43 / 45

    Prompt Anchoring

    Initial instructions shape AI reasoning and outputs.

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  • AI phenomena 44 / 45

    AI Authority Bias

    AI outputs can receive excessive authority.

    Explore
  • AI phenomena 45 / 45

    Algorithmic Amplification

    Algorithms can amplify patterns, preferences, and information bubbles.

    Explore
Back to the library

The learning path

Guided courses built on the same laws and library. Start with the roadmap; more tracks are on the way.

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The one page I wished existed

A study companion for how people actually think — sourced, free, and built by one designer.

Learn UX started with a simple frustration. Studying UX meant opening twenty tabs — Wikipedia, NN/g, research papers, half-right blog posts — and losing the thread every time. Laws were scattered, sources were unverified, and plenty of the explainers just got the science wrong.

So I built the single page I wished existed: one place where every law is sourced, every reference links back to the people who actually discovered it, and nothing is made up. Not a course, not a business — a study companion I use myself.

If a law here made something click for you, that's exactly why this exists. Found a shaky source, a broken link, or an experiment behaving oddly on your device? Tell me — every message gets read.

What makes this different

  • Every law is checked against original research
  • Every source links back to the original author or paper
  • No paywall — free to learn and free to share
  • Built by a practicing designer, not a content farm
  • Global search — find any law in seconds
Contact

Much love,
Asim