12 mins | 28 Sep, 2022

A primer on Mental Models

A Mental Model is the term used to describe your idea of how something works. We all have thousands of mental models (millions really, depending on how you break it down) which relate to every aspect of our lives. Everything from cleaning your teeth to boarding a plane. Without mental models we would be truly useless, having to learn everything we do from scratch every time we wanted to do anything (no one would ever get out of the house in the morning).

As we grow from infants into adults we learn how the world works around us and constantly add to our store of mental models. We use these then as a starting point for every task. We instinctively know (or at least have a good idea) of how a thing should operate through past experience.

One of the best things about mental models is they are transferable. You may not know exactly how your new coffee machine works, but you’ve used enough electronic appliances to get that capachino flowing pretty quickly.

Mental models are subjective. Yours are unique to you, as is the culmination of your personal life experiences. There are enough commonalities though that allow designers to apply some broad thinking in how most people will instinctively approach a task. Understanding the reasons behind this will help us create useful and intuitive experiences that complement human behaviour instead of conflicting with it.

How people form mental models

We start to form mental models from birth. Children learn rapidly through observation, watching the world around them and copying what they see. Every experience we have contributes to our understanding of the way things work and through repetition, we reinforce our beliefs around these.

The word belief is important here. Mental models are based on beliefs, not facts. It is not an actual blueprint of how something works, it is simply your personal understanding of how it should work. Therefore all mental models are prone to error, we can be completely wrong in our view of the mechanics of the world around us. Primitive people often believed it was vengeful spirits that caused disease (largely based on the evidence they had available to them). Over time more experiences uncovered different ideas until eventually, germ theory provided a more scientific reason to believe in how diseases are spread among us.

So, as we navigate the world by having new experiences and repeating old ones, we become familiar with different people, objects, technology, methods, cultures and concepts. We imitate others and figure some things out for ourselves. Some things we pick up easily, and others take a huge effort to understand. Ultimately, it's the collection of all our worldly experiences that go into our library of mental models which we use (either knowingly or unknowingly) to get things done.

Habit-forming mental models

Habits and mental models work well together. It is through the repetition of tasks that we sometimes learn new mental models (or refine old ones). A common one most people learn from a young age is tying your shoelaces. When you first try, it's difficult to understand the complexities of which lace should cross over the other, but through repeated attempts, we get it and eventually becomes second nature. Very few adults have to think about how to tie their shoe laces, they just do it. That's a mental model that's become habitual.

A mental model for tying shoe laces
A mental model for tying shoe laces

Technology is another area where we repeat the same actions often. There are lots of common actions in software that use similar patterns to get things done. Presented with a completely new application, it's highly likely you’ll be able to create a new document, save or delete something without having to learn how. That's because developers tend to stick to what users know (it's also why it can be a bad idea to step away from common mental models within software design).

Jakob’s Law

Jakob’s law (or Jakob’s law of the internet user experience) reminds us that, users spend most of their time on other people's websites than yours. Therefore, when they land on your website, they expect it works in the same way that other sites do. They have built up a mental model of how websites should work and they almost certainly would prefer yours to work in the same way.

This is true for broad concepts like site navigation, page structure and hierarchy, plus specific details like the logo in the top left will likely take me back to the home page. It's also true for types of websites, most eCommerce website designs for instance will follow common patterns (customers should instinctively know how to add an item to a cart and checkout).

It's really important then, to keep this in mind when designing a new website. If you don't follow pre-conceived ideas of how a website should work, you risk confusing your users and losing them.

Examples of mental models in web & app design

As discussed already, it is a good idea when designing a website or application to stick to common patterns, or tried and tested methods. This is because users will draw on their mental models of how things generally work in the same space and you want to make it as easy as possible for them to complete an action. Here are a few examples:

Hamburger menu navigation

Lots of websites use a hamburger icon (named because the 3 lines mimic a hamburger in a bun) to open/close its main navigation. This is especially true on mobile devices where space is an issue and the navigation needs to be hidden until needed. The 3 simple lines have become the default visual cue that the navigation is available here. Users instinctively know, that no matter where they are on a website, if they click that icon they will be able to access the main site navigation.

Mental model example: Hamburger menu

eCommerce shopping cart

eCommerce is an area of technology that relies heavily on mental models. Nearly all eCommerce stores follow the same basic layouts and include the same features. Merchants understand users want to spend time reviewing products, not learning how to purchase them. Therefore, a shopping cart will 99% of the time follow the same steps:

  • Add your product to a cart
  • Review & proceed to checkout
  • Add your payment & delivery details
  • Receive a confirmation of your order

That's what customers know, and it's what they expect, every time. Deviate from this and you risk losing the sale.

Mental model example: eCommerce shopping cart

Save icon

The save icon is an interesting one. When people first started using computers widely, it was most common to save files to a floppy disk, so it's only natural that designers of the day used this icon to denote ‘click here to save’. Over time though, technology evolved but the icon stayed. Even now, some software is shipped with a disk icon to represent save (even though no-ones used disks for years). Show a teenager an old floppy disk now and they’ll think you’ve 3D printed the save icon.

There is a shift currently within software toward autosave (meaning you never actually need to hit the save icon, your work is always saved up to date). Time will tell how this shift will effect our mental models of saving digital work.

Mental model example: Save icon

Back and forward buttons

Even the placement of forwarding and back buttons effect our understanding of how things work. In the western world, we read left to right and tend to do other things in a left-to-right motion. We generally perceive the left-hand side as representing the past and the right as the future. If we talk about the progression of a state or story, we tend to move from left to right.

Therefore, placing the back button on a web browser in the top left feels right to the user. If they want to go back, they will instinctively look to the top left of the screen. Similarly, a moving forward action (like a form submission or next page) will generally be better placed in the bottom right (as that's where users will look first).

Mental model example: Back button

Sign-up registration (email confirmation)

Signing up for a service or creating an account online typically follows the same pattern. You enter your email address, which then needs to be validated by sending you an email with a link to click back to the application. This has become so commonplace that you almost don't need to explain it anymore, users know that by entering their email address, they are almost certainly going to have to open their email client to click something. Because we signup for so many services these days, this has become a habitual mental model (like tieing your shoelaces).

There are different ways you could manage the signup of a new service, you don't have to follow that same pattern. As users are so comfortable with it though, trying something new or unfamiliar would almost certainly be met with some friction by users.

Mental model example: email signup

How to use mental models in UX Design

Understanding mental models

As UX Designers, we can use knowledge of how those we are designing for view an application and its functions to create better, more intuitive experiences. In order to apply this kind of thinking, we must first understand what our user's mental models are (their level of expertise). We can do this through various methods. Here are a few options to get started:

  • User testing: The best approach to understanding users is typically going to be with real testing. Monitoring what people do in a given situation (rather than what they say they do) will highlight where users are comfortable with features or layouts (and find them intuitive to use) and where they get stuck or miss things completely. If you have the resources to test properly, this is going to give you some great insight.
  • Card sorting exercises: If you can’t do actual user testing, card sorting can be a simple way to get some quick data on how users think something should work. Card sorting is an exercise designed to sort the hierarchy of content (pages) or features in a website (or another kind of application). It’s a great group activity for project stakeholders in a workshop and will give you some visibility of how people think content/features should be categorised and how important each item might be. You can use this exercise to gain some idea of how someone thinks an overall website/app should operate.
  • How might we exercise: A ‘How Might We’ exercise is designed to get people thinking about problem-solving. You start with a problem you have, then turn that into a statement “How might we… [solve this problem]”. The answers people give to these statements will provide insight into how those people would approach something. This will help you understand their mental model around solving any given problem.
  • Cause and effect diagram: A cause and effect exercise will also provide insight into how users think. By asking “What caused this?” and “What effect will it have?” you gain an understanding of a user's view of how something should operate. There are different ways to approach cause and effect investigations, but the point is typically to probe a little deeper into how and why things really happen.

There are lots of exercises available to us as UX researchers, these are just a few examples. You can probably find more that will give you different kinds of insights. The idea is to look really deeply into a user's beliefs of how the world around them works and then use that knowledge to inform your next steps.

Applying mental models

Once you have a good understanding of your user’s mental models around the subject you’re designing for and the elements that will help them solve their problems, you can use that to improve the end result.

  • Site mapping: From a high level, you will want to ensure your site map meets a commonly understood format. User’s typically expect certain types of content to be in certain places and you can use a broad mental model to decide where your pages or sections will be most appropriate. There is a mental logic to most document mapping, whether it's a Website, App, eBook or Document Wiki, unless you’re building something truly unique and new, it's wise to stick with common arrangements.
  • Content architecture: As well as document mapping, your content architecture should follow user expectations (this is where card sorting can be particularly useful). Serving up the most important content first, then gracefully degrading down a hierarchy of relevance will ensure that most users will get what they are looking for as efficiently as possible.
  • User journey mapping: A user journey is a route a user follows from first landing on a page, to where they end up (hopefully with the desired action they had in mind completed). As a designer, your job is to create an efficient user journey that informs, educates or entertains the user along the way so when they get to their end goal, they either complete an action or feel they got what they came for. By understanding a user's pre-conceived ideas of ‘how this site should work’ you can create more informed user journeys that get the job done.
  • Wireframing: Wireframing allows us to detail specific elements that will be added to a page and will lead to a blueprint of your site/app before getting to UI Design. If our research on mental models tells us a user expects to login in a certain way, we can wireframe that to show the specific details and nuances of the technology we’re working with. Wireframing can be used as an early-stage prototype to test out ideas and get things down in visual form more quickly than it takes to do a full UI prototype.

Again, there are lots of ways designers can approach ensuring their research on mental models is effectively applied to a project. These are some typical starting points but in our field, it's always good to look at innovative and new approaches to apply our learning.

The problems that stem from mental models

When you start thinking deeply about mental models, there are certain problems that arise. If you want to do this kind of research and apply it to your design work, it's worth considering the pitfalls and where you might come unstuck.

Thinking about mental models

What people perceive is subjective

We each have our own view of the world as we perceive it slightly differently. That means one person's mental model might be different to another. Cultural differences, individual tastes, life experiences and every other personal event that's led up to a certain point will have an effect on your particular subjective view of how something works. You might be surprised how an individual's framing of something or approach to a given task may effect their view of it.

Mental models can be incomplete

A mental model can (and often is) based on incomplete facts or misunderstandings. Our human brains have evolved to jump to conclusions by using heuristics to fill in incomplete information. It's a form of protection that served us well in the early hunter-gathering stage of human evolution, but in the modern world, it can lead us to make snap, ill-informed decisions (try telling the system 1 brain it's wrong though…it's probably far too stubborn to listen).

Designers know too much

As a designer, the biggest thing you should take away from this, is that your mental model of anything you’ve poured hours of time into is much (much!) more detailed than any user that's going to be interacting with it. If you’ve developed a user journey through a website, considered all the intricate details of a page layout and designed each feature available, you have a very thorough working knowledge of exactly how it should operate. Your users do not. They are coming in blind discovering it for the first time and may have different goals in mind than you. How something is designed to be used and how it's actually used can be very different things.


Mental models are part of human life and have evolved to help us over thousands of years. They are continuously changing and can be incredibly powerful but also woefully inaccurate. There are no correct mental models, only our own individual and personal views of the way the world around us works.

Those who understand these concepts can use them to build more effective and intuitive experiences. They can also be used to manipulate the human brain and trick us into scenarios we’d rather avoid.

As a designer, learning how to understand people's mental models can be hugely beneficial in creating human-centric applications that help to solve real problems. It can also help ensure we get the smaller details right which leads to less friction and an overall smoother experience.

Mental models are really just a starting point though, if this type of thinking is interesting to you I encourage you to investigate further as there are many tangents to follow from here.

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