A Guide to Mental Models

What is a Mental Model?

Mental models are a representation of the user’s perceived reality. A mental model is what the user believes about a system based on a person’s past experiences and what they think they know about a system. They are unique for each user as it is from their point of view, reaching from their beliefs and experiences. Many industries use mental models, including technology, business, and psychology. They help to describe how the user defines steps around a task and how it differs from your definition or the “industry standard” definition. A mental model is not based on facts! When the system doesn’t match the user’s mental model and expectations people feel bad for making a mistake, it lowers the perceived value of the service, and it seems like your application is broken. Mental models are not necessarily ever complete as they can change as soon as a person changes, either their thought process or point of view.

A mental model diagram or map is an illustration of a user’s thought process. A mental model map identifies the beliefs, behaviors, and emotions while the user is completing a task.

What is a Mental Model in UX?

For UX design, a mental model is what the user believes about how the system should work. A mental model can be used by the UX designer to help develop designs and experiences that make sense to the users. The mental model can be used to either stick with the workflow the user is used to or to figure out a way to help them learn a new design. Remember that the user’s mental model is very different from the UX designer’s. Also, remember that every user has a different mental model.

“Individual users each have their own mental models, and different users may construct different models of the same user interface. Further, one of usability’s big dilemmas is the common gap between the designers’ and users’ mental models.” – Jakob Nielsen, Nielsen Norman Group.

Jakob’s Law of the Internet User Experience states that “users spend most of their time on websites other than yours. Thus, a big part of customers’ mental models of your site will be influenced by information gleaned from other sites.”

Mental models are more about the process than design in many ways. It can be a design shortcut to represent a technical process, but it is about mapping a user belief/expected workflow to how the system works or to more efficient workflows. The design element of a letter icon or paper airplane represents the email workflow. A similar example is when a user is used to doing 4 steps in their previous workflow, but the system wants them to do it in 2 steps for the same outcome. If the UX designer doesn’t handle the mental model expectation well, the user could be more confused by the fewer steps.

Why are Mental Models Important in UI Design?

Mental models play a very important role in user interface (UI) design. Mental models help designers understand what users expect from a system and how they will likely interact with the interface. Users form mental models by drawing on their experiences with other websites, applications, and everyday interactions. They expect their interactions with your service to be similar, or the same. If you change behavior, make it easy for them to understand by mapping the new mental model to their mental model of how things work currently.

What is an Example of a Mental Model?

A mental model is the user’s perception and explanation of how things work. In the example of the mental model map above, you can see during the registration section, the user registers and pays for the marathon. The runner expects an e-commerce like a checkout process from other online purchases, but actually, there is a mail-in form that makes them nervous. In the training section, the user expects to be running marathon-length runs to train, but in reality, they are not supposed to. In the planning section, there is the choice to stay the night at the start line, at a hotel, or to drive up the morning of the event. Not having been in the area before, there wasn’t much expectation of the camping, so the runner chose to drive up the day of the race. After being there, the mental model of the participant changed when they noticed the camping options are actually nice.

Some mental model maps have additional information below the horizontal line. This bottom area is where you can show the system side of the map and can be services, processes, or information. An example is under registration; there could be a specific page on the website or an email. Under the training and training plans would be the multiple blogs and books the user read to discover and decide which training plan would work best.

To see more examples of mental models, read 10 Examples of Mental Models in UX Design.

Interviewing and Testing to Discover Mental Models

Because mental models are so important in UI design, mental model testing has become a popular type of user research. It involves formally asking people to explain how they think a system works and then testing to see if the mental model matches up with how the system actually works. In mental model testing, researchers ask participants questions such as:

• What do you expect when entering your password every time you log in?

• Where would you expect to find the terms and conditions related to the privacy policy?

• What is the next step you expect after entering your query when searching for images?

Questions like these help researchers confirm that mental models are accurate. If mental models don't match up with the mental model of a system, the mental model testing will highlight this gap and provide insight into how to resolve it.

The first thing to remember about these interviews is that it should be a conversation. Not only do you want the user to guide the conversation, but you want them to be talking most of the time. One easy way to do that is by making sure your questions are open-ended. Use who, what, where, when, why, and how and not did, have, are, were, or will. Don’t ask about the tools or features they are using. Instead, ask what they are trying to accomplish and why. Be very careful about using specific terminology if the user has not already used it; many people refer to things differently. The final thing to consider is be sure you ask the user about a recent experience. The more time has passed, the more likely the user may misremember their experience.

If you want to change your users' mental models - or if your mental model is different from that of most people and you're trying to build a better mental model for them - there are two important things to keep in mind:

• First and foremost, mental model testing will help you understand the mental models that already exist and how they relate to each other;

• Second, mental models are not permanent fixtures of a person's mental world, but rather things we continuously create and recreate as new situations arise. Once users establish a mental model for your system, they will continue to draw on it as long as mental resources remain plentiful. When mental resources are low or when something happens that doesn't quite fit into the mental model, mental models will change.

In mental model testing, participants typically provide a natural explanation of how their mental model works and what factors influence it. Don't assume a mental model is true, but ask questions to understand it. Then mental model testing can help you compare mental models with mental models of actual systems to see if there are any differences and how they relate to each other. In addition, mental model testing can show what factors affect mental models and which mental resources people draw on to form mental models.

Another useful guide is to use the 5 Whys. Note that 5 is not necessarily a required number of whys to find the root of users’ mental models. A 5 whys session starts with a problem statement from the user; for example, the user says they couldn’t do something or didn’t like something. You ask why. “Why questions” are very good at uncovering user mental models because you want to know the “why” behind what you observe the user is doing. Make sure you let them know that you are following the 5 Whys process, so they are not annoyed or offended.

A quick example: Ask a user what they use for grocery lists

What do you use for grocery lists?

My phone.

Why your phone?

I almost always have my phone with me.

What app do you use on your phone?

Google Docs.

Why do you use Google Docs?

I already use Google Docs for other things.

Why do you use Google Docs for lists?

So my spouse and I can both edit the list at the same time and see the updates immediately.

While interviewing or user testing, it is advantageous to have the user to think out loud so you can hear what they are thinking. “Think out loud” sessions are vitally important when conducting these interviews remotely.

Conclusion

Mental models are a not so secret way to design for great user experiences. Each user has a unique mental model or belief about how things are supposed to work. A mental model map is a great visual representation of the user’s expectations that increases a project’s success.

Further Reading and References

• “Mental Models: Aligning Design Strategy with Human Behavior” by Indi Young
• “Mental Models” by Jakob Nielsen – NNG