Tam Blog

30 Laws of UX — A Guide to User Experience Design

Introduction

Laws of UX is a collection of 30 psychology and design principles compiled by Jon Yablonski — "laws" that help designers and developers understand why users behave the way they do when interacting with an interface.

This post summarizes all 30 laws into 5 easy-to-remember groups, one sentence each, along with concrete applications for the Samcare website — hopefully useful for anyone working on e-commerce, landing pages, or any product with real users.

Group 1 — Cognition

How the brain takes in and processes information from an interface.

  1. Aesthetic-Usability Effect — Beauty creates a feeling of ease of use (even when the UX is actually the same).
  2. Cognitive Bias — The brain has systematic thinking errors that affect users' decisions.
  3. Cognitive Load — Don't make users think too much; every extra decision is a barrier.
  4. Mental Model — Users expect a UI to work like things they're already used to.
  5. Selective Attention — Users only see what's relevant to their goal — the rest is ignored.
  6. Working Memory — Short-term memory is limited; don't ask users to hold too much information at once.

Group 2 — Decision Making

How users make decisions when faced with options.

  1. Choice Overload — Too many choices → paralysis; users give up choosing entirely.
  2. Hick's Law — The more choices, the longer the decision time (logarithmically).
  3. Occam's Razor — The simplest solution usually wins.
  4. Paradox of the Active User — No one reads the manual; users just click and figure it out.
  5. Tesler's Law — Every system has an amount of complexity that can't be removed — the question is who bears it: the user or the developer?

Group 3 — Memory

How users remember and forget their experience with a product.

  1. Miller's Law — The brain holds about 7 (5–9) items at once in working memory.
  2. Serial Position Effect — Users remember the beginning and the end clearly, and forget the middle.
  3. Von Restorff Effect — Whatever is different is remembered longer.
  4. Zeigarnik Effect — Unfinished tasks haunt memory more than completed ones.
  5. Peak-End Rule — Users judge an entire experience by its highest peak and its ending — not the average.
  6. Chunking — Information split into small, meaningful groups is easier to remember.

Group 4 — Vision & Grouping (Gestalt)

How the eye groups elements together when looking at an interface.

  1. Law of Proximity — Elements near each other are perceived as a group.
  2. Law of Similarity — Elements that look alike are perceived as related, even when separated.
  3. Law of Common Region — Elements within the same frame/border are perceived as a group.
  4. Law of Uniform Connectedness — Elements connected to each other (a line, an arrow) are seen as the most related.
  5. Law of Prägnanz — The brain simplifies complex shapes into the simplest possible form.

Group 5 — Behavior, Motivation & Interaction

What makes users continue, give up, or click faster.

  1. Goal-Gradient Effect — The closer to the goal, the harder users try — progress bars exploit this effect.
  2. Flow — A state of deep focus when challenge and skill are balanced.
  3. Pareto Principle — 80% of results come from 20% of causes — focus on the important 20%.
  4. Parkinson's Law — Work expands to fill the time allotted to it.
  5. Fitts's Law — The time to click a target is proportional to the distance and inversely proportional to its size (a big button near the cursor = faster).
  6. Doherty Threshold — System response under 400ms makes users feel productive; above that, they feel annoyed.
  7. Jakob's Law — Users expect your site to work like the sites they already use — don't break conventions.
  8. Postel's Law — Be liberal in what you accept from users, strict in what you output (forgiving inputs, strict outputs).

Practical application for Samcare

Theory is one thing; turning it into conversion is another. Here are 6 priority applications for the Samcare website:

Priority Law Application Expected benefit
1 Hick + Choice Overload Trim the category menu, consolidate product filters Lower bounce on the shop page
2 Peak-End Rule Optimize the checkout feeling + a thank-you email with a voucher Increase repeat purchases
3 Doherty Threshold Cache + optimize images on product pages to load <400ms Lower bounce, better SEO
4 Jakob's Law Cart/checkout layout like Shopee/Tiki Familiar = higher conversion
5 Goal-Gradient A 3-step checkout progress bar (1/3 → 3/3) Reduce cart abandonment
6 Serial Position Put the CTA + USP at the top and bottom of product pages Increase add-to-cart rate

Conclusion

These 30 laws aren't disjointed "tricks" — they're how the user's brain actually works. A good designer doesn't memorize all 30 names, but knows when to apply which.

How to use them in practice: - Before sketching a new flow: review the Decision Making group (Hick, Choice Overload, Tesler). - Before launch: check the Memory group (Peak-End, Serial Position) — especially the checkout and thank-you steps. - When auditing an old site: use the Cognition group (Cognitive Load, Mental Model, Jakob) — most UX bugs live here.

Original reference: lawsofux.com — Jon Yablonski.

Share this post