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Laws of UX – Principle Pt.2

Web Design

3 minute read

design and UX books

The Laws of UX – Principle Pt.2

In the world of UX design, principles are our guiding lights. Welcome to Part 2 of our exploration into the fundamental laws that shape user experiences. If you haven’t checked out Part 1 yet, be sure to catch up on “The Laws of UX – Heuristic” for insights into heuristic, aesthetic-usability effect, Fitt’s Law, goal-gradient effect, and more. In this sequel, we dive into five more principles that every UX designer should know.

The Principle UX laws covered in this blog article include:

Doherty Threshold

At the heart of the Doherty Threshold is the idea that productivity soars when a computer and its users interact at a pace (<400ms) that ensures that neither has to wait on the other. For UX designers, this principle underscores the importance of providing system feedback within 400 ms, keeping users engaged and enhancing productivity. Visual engagement tools like animation and progress bars can make wait times more tolerable, and adding purposeful delays can instill a sense of trust.

Occam’s Razor

Occam’s Razor, attributed to the medieval philosopher William of Ockham, advocates choosing the simplest hypothesis when presented with competing solutions that predict equally well. In UX design, this principle encourages us to minimise complexity from the outset. Analyse and remove unnecessary elements without compromising overall function, and consider completion only when no additional items can be removed.

Pareto Principle (80/20 Rule)

The Pareto Principle, which asserts that roughly 80% of the effects come from 20% of the causes, offers valuable insights for UX designers. Inputs and outputs are often unevenly distributed, so it’s essential to focus effort on areas that will bring the most significant benefits to the majority of users. This principle can help streamline user experience strategy.

Postel’s Law (Robustness Principle)

Postel’s Law advises being liberal in what you accept and conservative in what you send. It’s a principle that encourages empathy, flexibility, and tolerance in designing interfaces. Resilient designs anticipate various user actions and input, ensuring clear boundaries and feedback. By accommodating variable input and providing clear guidance, UX designers create more accessible and reliable systems.

Tesler’s Law (The Law of Conservation of Complexity)

Larry Tesler’s Law reminds us that for any system, there is a certain amount of complexity that cannot be reduced. UX designers must deal with this inherent complexity, making sure it’s assumed by the system rather than the user. The burden should be lifted from users as much as possible during design and development, without oversimplifying interfaces to the point of abstraction.


In this journey through the Laws of UX – Principle Pt.2, we’ve uncovered more principles that shape the user experience landscape. We’ve delved into the Doherty Threshold, Occam’s Razor, Pareto Principle, Postel’s Law, and Tesler’s Law. These principles provide valuable insights into creating user-friendly designs.

Stay tuned for “The Laws of UX – Principle Pt.3” as we delve into the fascinating world of GESTALT and unravel the mysteries of visual perception in UX design. In the meantime, put these principles into practice, and you’ll be well on your way to crafting exceptional user experiences.

If you’re ready to turn these insights into tangible results, we’re here to help. Our experienced team of designers and developers is eager to collaborate with you on your next bespoke software or website project. To get started, why not book a free 30-minute consultation with our team? Let’s discuss your ideas, challenges, and aspirations. Together, we can transform your vision into a reality that your users will love.