Foundational Design Laws

Field	Value
Type	Agent Reference
Source	~/.copilot/agents/_refs/senior-ux/cognitive-laws.md
Description	Not specified

Source Content

Foundational Design Laws

These principles come from decades of research. They are not opinions. They are how human brains work. Apply them to every decision.

How People Think (Cognitive Load)

Hick’s Law — More choices slow people down. Keep primary actions to 3–5 per screen. Use progressive disclosure to hide the rest until needed. Named after William Edmund Hick and Ray Hyman, 1952.

Miller’s Law — Working memory holds about 7 items (plus or minus 2). Chunk related information into groups of 3–5. Never show more than 5–7 ungrouped items. George Miller, 1956.

Cognitive Load Theory — Every element on screen costs mental energy. If removing something doesn’t hurt the user’s ability to complete their task, remove it. John Sweller, 1988.

Tesler’s Law — Complexity cannot be destroyed, only moved. Your job is to absorb complexity into the system so the user doesn’t have to carry it. Larry Tesler, Xerox PARC.

Occam’s Razor — When two designs solve the same problem, the simpler one wins. Subtraction is a design skill. Adding is easy. Removing takes courage.

Krug’s First Law of Usability — “Don’t make me think.” If a user has to stop and wonder what something means or where to click, you’ve created friction. Steve Krug, 2000.

Satisficing — People don’t read pages. They scan. They don’t choose the best option. They choose the first reasonable one. Design for scanners and satisficers, not careful readers. Herbert Simon, 1957; applied to web by Krug.

How People See (Perception & Attention)

Fitts’s Law — Bigger targets closer to the user’s current position are faster to reach. Primary actions get the largest tap targets. Minimum 44×44px on mobile, 48×48px recommended. Paul Fitts, 1954.

Von Restorff Effect — The item that looks different is the one people remember. Use visual contrast for calls to action and critical information. Everything else should recede. Hedwig von Restorff, 1933.

Serial Position Effect — People remember the first and last items in a sequence best. Put the most important things at the beginning and end. Hermann Ebbinghaus.

Banner Blindness — Users automatically ignore anything that looks like an advertisement. Never put important content in decorative boxes, sidebars, or ad-shaped containers. Jakob Nielsen, 2007.

Change Blindness & Inattentional Blindness — People miss changes outside their focus. Animate transitions. Use motion to draw attention to state changes. Never rely on passive notifications for critical information. Daniel Simons and Christopher Chabris, 1999.

Gestalt Principles — The brain groups visual elements automatically: proximity (close = related), similarity (same style = same function), closure (we complete incomplete shapes), common region (shared boundary = grouped), continuity (we follow lines and curves). Use these to create visual hierarchy without relying on lines and borders. Max Wertheimer, Kurt Koffka, Wolfgang Köhler, early 1900s.

How People Behave (Interaction & Motivation)

Jakob’s Law — Users spend most of their time on other websites and apps. They expect yours to work like those. Don’t reinvent navigation, forms, or checkout flows without a very good reason. Jakob Nielsen.

Doherty Threshold — System response must feel instant (under 400ms) to maintain the user’s flow state. If something takes longer, show progress feedback immediately. Not after a delay — immediately. Walter Doherty and Ahrvind Thadani, IBM, 1982.

Zeigarnik Effect — People remember incomplete tasks better than completed ones. Use progress bars, checklists, and step indicators to keep people oriented and motivated. Bluma Zeigarnik, 1927.

Peak-End Rule — People judge an experience based on its most intense moment and its ending, not the average. Make success states feel great. Make the final interaction memorable. Daniel Kahneman.

Goal-Gradient Effect — People accelerate as they approach a goal. Show progress. Make the end feel close and achievable. Clark Hull, 1932.

Endowment Effect — People value what they’ve already invested in. If a user has entered data or made progress, protect that investment. Never let form data disappear. Never lose their work. Richard Thaler, 1980.

Self-Determination Theory — People are motivated by autonomy (choice), competence (mastery), and relatedness (connection). Interfaces should offer meaningful choices, make users feel capable, and create a sense of belonging. Deci and Ryan, 1985.

How People Read and Scan (Layout & Visual Hierarchy)

F-Pattern — On text-heavy pages, users scan in an F shape: across the top, then partway across a lower line, then down the left side. Place critical content on these natural scan paths. Jakob Nielsen, 2006.

Z-Pattern — On pages with less text (landing pages, dashboards), users scan in a Z shape: top-left to top-right, diagonally to bottom-left, then across to bottom-right.

Visual Hierarchy — Guide attention in this order: size first, then color, then contrast, then position. Every screen should have exactly ONE dominant focal point that answers the question “what should I do here?”

Whitespace is structure. Generous spacing is not wasted space. It’s what makes content scannable, reduces cognitive load, and creates visual breathing room. Cluttered screens feel overwhelming. Spacious screens feel manageable.

Law of Proximity — Items near each other are perceived as related. Group related controls and content with spacing. Separate unrelated items with whitespace — not lines. Lines add clutter. Space creates clarity.

Law of Similarity — Items that look alike are perceived as having the same function. Keep consistent styling for elements that do the same thing across the entire product.

Law of Common Region — Items inside a shared boundary (card, container, box) are perceived as a group. Use cards and containers intentionally, not decoratively.

How People Make Mistakes (Trust & Error Prevention)

Nielsen’s Error Prevention — Prevent errors before they happen. Disable invalid actions. Use smart defaults. Show constraints upfront. The best error message is the one that never appears.

Poka-Yoke — Design so the wrong action is impossible, or immediately reversible. Undo is always better than “Are you sure?” confirmation dialogs. Shigeo Shingo, Toyota Production System.

Recognition Over Recall — Show people their options instead of making them remember. Autocomplete beats empty text fields. Menus beat memorized commands. Visible choices beat hidden ones. George Miller’s research, applied by Nielsen.

Aesthetic-Usability Effect — People perceive beautiful interfaces as easier to use, even when they aren’t. Polish and visual quality build trust. Sloppy interfaces feel untrustworthy. Masaaki Kurosu and Kaede Kashimura, 1995.

Social Proof — When people are uncertain, they look at what others have done. Show reviews, ratings, usage counts, and testimonials to reduce decision anxiety. Robert Cialdini, 1984.