Great UX doesn't happen by accident. The world's best digital products are built on cognitive science principles that have been validated through decades of research. Here are the laws every designer should internalize.
Hick's Law
The time it takes to make a decision increases with the number and complexity of choices. Implication: Simplify your navigation. Reduce form fields. One CTA per page. Decision fatigue is real.
Fitts's Law
The time to acquire a target depends on distance and size. Implication: Make buttons big enough and close enough to where users are already looking. Mobile buttons should be at least 44px.
Miller's Law
The average person can hold about 7 (plus or minus 2) items in working memory. Implication: Chunk information into groups. Use progressive disclosure. Don't overwhelm the user.
Jakob's Law
Users spend most of their time on OTHER websites. They expect your site to work like sites they already know. Implication: Don't reinvent the wheel on navigation, forms, or checkout flows.
Users prefer your site to work the same way as all the other sites they already know. — Jakob Nielsen
The Peak-End Rule
People judge an experience based on how they felt at its most intense point and at its end. Implication: Design memorable positive peaks (delight moments) and strong endings (confirmation screens, thank-you pages).
The Law of Proximity
Objects near each other are perceived as related. Implication: Group related form fields. Place labels directly above their inputs. Keep CTAs close to the value proposition they respond to.
Applying These Laws in Practice
You don't need to apply all laws to every design decision. But keeping them in the back of your mind when something "feels off" often reveals the problem instantly.