Reading room Comprehensive study

Design Codex

I’ve created a clear and user-friendly guide featuring essential design laws and principles for you to learn and apply in your work. As the field of design evolves, this codex will grow with it, regularly updated with new insights and improvements to remain relevant and practical.

Current number of laws and principles: 19

Psychological
Jakob's Law

Users' expectations are shaped by their experience with other sites.

Psychological
Miller’s Law

The average person can keep about 7 (± 2) items in their working memory.

Psychological
Hick’s Law

The time to make a decision increases with the number and complexity of choices.

Psychological
Peak-End Rule

People judge an experience by its peak and its end.

Design & LayoutGestalt principle
Law of Proximity

Objects that are near each other tend to be grouped together.

Design & Layout
Understanding color codes

Colors are represented differently across mediums.

Usability & Interaction
Fitts's Law

The time to acquire a target is a function of the distance to and size of the target.

Usability & Interaction
Affordance Theory

The design of an object should suggest how it is to be used.

Usability & Interaction
Tesler’s Law

There is a certain amount of complexity in a system which cannot be reduced.

Usability & Interaction
Aesthetic-Usability Effect

Aesthetic products are perceived as easier to use.

Usability & Interaction
Doherty Threshold

Productivity soars when a computer and its users interact at a pace (< 400 ms) that ensures that neither has to wait on the other.

Behavioral Economics & Motivational
Sunk Cost Fallacy

People hesitate to quit a strategy due to past investments, even if future benefits don't justify ongoing commitment.

Behavioral Economics & Motivational
Pareto Principle

Roughly 80% of the effects come from 20% of the causes.

Behavioral Economics & Motivational
Goal Gradient Effect

The tendency to approach a goal increases with proximity to the goal.

Behavioral Economics & Motivational
Parkinson’s Law

Work expands to fill the time available for its completion.

Behavioral Economics & Motivational
Endowed Progress Effect

A phenomenon where people are more likely to complete a goal if they have a head start.

Behavioral Economics & Motivational
Cost-Benefit Principle

Users weigh the cost of their action (effort) against the benefits they will receive.

Behavioral Economics & Motivational
Scarcity Principle

Items in short supply are perceived as more valuable.

Ergonomics & Accessibility
Occam's Razor

Among competing hypotheses that predict equally well, the one with the fewest assumptions should be selected.