10 UX Laws Senior Designers Actually Use
1. The Difference in UX Laws Senior Designers Actually Use
Compared with laws often mentioned at the introductory level, in practice, principles for behavioral design such as complexity, speed, trust, memory, and motivation are used more often.
- Junior designers first look at screen elements and layout, but seniors look at what burden the user feels and what actions that leads to.
- Good UX laws are not knowledge for memorization, but criteria for judgment in concrete product moments such as checkout, onboarding, settings, search, and cancellation flow.
2. Laws for Handling Complexity and Input
To reduce user mistakes, rather than trying to eliminate complexity, you need to decide how much burden the system will absorb.
- Tesler’s Law: Every system has irreducible complexity, and that burden must be borne by either the user or the product team.
- Postel’s Law: Accept user input flexibly, and provide system output in a predictable and clean way.
- Chesterton’s Fence: Before removing an element of an existing product that looks outdated, first understand why that element was created.
3. Laws for Designing Speed, Change, and Trust
The responsiveness users perceive and the scale of change have a greater impact on product trust than actual speed.
- Doherty Threshold: Responses within 400ms feel conversational, and for tasks that take longer, perceived speed should be designed with skeletons, optimistic UI, and progress indicators.
- Weber’s Law: Because users notice only changes beyond a certain level relative to what already exists, the accumulation of small changes reduces resistance more than a large redesign.
- Labor Illusion: In search, comparison, and analysis products, rather than results appearing too instantly, they can be trusted more when a “process at work” is visible.
4. Laws that Move Memory and Motivation
Users remember unfinished states, goals that feel close, traces of their own participation, and the final moment more strongly than the average of the entire experience.
- Goal Gradient Effect: As the goal gets closer, motivation increases, so onboarding checklists or profile completion can be designed with the starting point as an in-progress state rather than 0.
- Zeigarnik Effect: Unfinished tasks are remembered longer, so interrupted states such as draft, cart, and course progress themselves become a reason to return.
- IKEA Effect: Experiences that users choose and configure themselves early create a sense of ownership and reduce drop-off.
- Peak-End Rule: Because users remember the overall experience around the most intense moment and the final moment, success screens, cancellation flows, and error states must also be designed to the end.
