Users spend most of their time on other sites, and they prefer your site to work the same way as all the other sites they already know.
By Jon Yablonski   |   2020   |   Laws of UX

Origins

Jakob’s law (also known as “Jakob’s law of the internet user experience”) was put forth in 2000 by usability expert Jakob Nielsen, who described the tendency for users to develop an expectation of design conventions based on their cumulative experience from other websites.1 This observation, which Nielsen describes as a law of human nature, encourages designers to follow common design conventions, enabling users to focus more on the site’s content, message, or product. In contrast, uncommon conventions can lead to people becoming frustrated, confused, and more likely to abandon their tasks and leave because the interface does not match up with their understanding of how things should work. The cumulative experience that Nielsen refers to is helpful for people when visiting a new website or using a new product because it informs their understanding of how things work and what’s possible. This underlying factor is perhaps one of the most important in user experience, and it is directly related to a psychological concept known as mental models.

Mental Models

A mental model is what we think we know about a system, especially about how it works. Whether it’s a digital system such as a website or a physical system such as a checkout line in a retail store, we form a model of how a system works, and then we apply that model to new situations where the system is similar. In other words, we use the knowledge we already have from past experiences when interacting with something new. Mental models are valuable for designers because we can match our designs to our users’ mental models to improve their experience by enabling them to easily transfer their knowledge from one product or experience to another, without the need to first take the time to understand how the new system works. Good user experiences are made possible when the design of a product or service is in alignment with the user’s mental model. The task of shrinking the gap between our own mental models and those of the users is one of the biggest challenges we face, and to achieve this goal we use a variety of methods: user interviews, personas, journey maps, empathy maps, and more. The point of these various methods is to gain a deeper insight into not only the goals and objectives of our users but also users’ preexisting mental models and how all of these factors apply to the product or experience we are designing.

Jakob’s law isn’t advocating for sameness in the sense that every product and experience should be identical. Instead, it is a guiding principle that reminds designers that people leverage previous experience to help them in understanding new experiences. It is a not-so-subtle suggestion that (when appropriate) designers should consider common conventions that are built around existing mental models to ensure users can immediately be productive instead of first needing to learn how a website or app works. Designing in a way that conforms to expectations allows users to apply their knowledge from previous experiences, and the resulting familiarity ensures they can stay focused on the important stuff—finding the information they need, purchasing a product, etc. The best piece of advice I can give in regard to Jakob’s law is to always begin with common patterns and conventions, and only depart from them when it makes sense to. If you can make a compelling argument for making something different to improve the core user experience, that’s a good sign that it’s worth exploring. If you go the unconventional route,

Karmen Guevara, human–computer interaction pioneer