5 minutes read

I live in a small village near to Cambridge in the UK. In my village are a number of mini-roundabouts such as the one shown below. For those unfamiliar with roundabouts (another great British invention) they are circular road junctions that are supposed to be safer and provide better traffic circulation than a more traditional junction. Drivers must give way to traffic already on the roundabout and then drive around the centre to get to their desired junction. If everyone does this then roundabouts can work well. However, the mini-roundabouts in my village have a problem, one that is caused by a design that does not properly consider the user’s model. Let me explain.

A mini-roundabout in my village

The problem with mini-roundabouts

A mental model is the internal model that someone uses to quickly understand and interact with things in the real world. Rather than starting from scratch each time we are presented with a situation we will intuitively employ an internalised mental model which has been built up from real-world experience. In this instance users of the mini-roundabout are likely to employ one of two internal mental :

  1. A roundabout – where drivers must give way to traffic to the right
  2. A road junction – where drivers on the main road have right of way

The key problem with the mini-roundabouts in my village is that the mental model utilised by users can differ, leading to potentially very dangerous situations. Imagine for example two cars approaching the mini-roundabout. The first driver treats it like a junction, because he thinks that it looks more like a junction than a roundabout. He will therefore assume that he has right of way and that the driver approaching from the side road will stop to let him through. The second driver on the other hand treats it like a roundabout. She assumes that she has right of way and that the driver on the main road will stop to let her enter the roundabout. If both drivers blindly follow their chosen mental model, then it’s going to result in an almighty CRASH as each incorrectly assumes that the other will give way.

This lack of a consistent mental model is down to the poor design of these and countless other mini-roundabouts. The design does not help the user to select the intended mental model to use (i.e. a roundabout) because at a glance it could be interpreted as a roundabout, or as a junction. A better design would make it clearer which mental model to use, such as the example below which uses a sign and raised curb to stop vehicles from driving straight over the mini roundabout and to re-enforce the fact that a mini-roundabout is still a roundabout.

Mini-roundabout with sign and raised curb
A better design for a mini-roundabout

The importance of mental models

Mental models can have a huge impact on how users perceive and use something. Go against the mental model used by the vast majority of users, or make it unclear which mental model to use, and you’ve got the recipe for something that is confusing and unintuitive. So how do you go about designing and services that are aligned with a user’s mental model? How do you help users to select the intended mental model to use? Here are some tips for doing just this.

Find out the current mental model

To create products and services that are aligned and in-tune with a user’s mental model, you should first find out what that mental model looks like. For example, if you’re designing an app or website to allow users to choose and configure a new car, you will want to find out how users go about doing this at the moment. Do they have a mental or even physical list of options they want? Do they have a shortlist of cars? How do they expect to be able to configure a car? Would they even expect to be able to do this online, rather than having to go to a dealership?

Interviews and observation are the best way to discover a user’s mental model. Ideally you can observe users as they undertake a task and then ask them to explain why they did what they did. Observing users first hand isn’t always possible so an alternative can be to ask users to walk you through their process, ideally by talking about a recent experience.

You can use a mental model map such as the one below to help map out the user’s mental model in detail. Mental model maps outline the steps, considerations and thought processes that users go through when completing a task, such as choosing a film to watch. Indi Young’s excellent Mental Models book has lots more information about creating and using mental model maps.

Mental model map by Indi Young
An example mental model map from Indi Young’s Mental Models book

Align with your user’s mental model

With a better idea of what your user’s mental model looks like you can start to design a product or service that is aligned with it. You don’t have to rigidly stick to the mental model, but if a product or service behaves very differently from how a user expects it to, then it’s going to lead to problems. Imagine for example if some car manufacturers put the accelerator pedal on the right, and others put it on the left!

Uber, the popular taxi service is a good example of a service that is innovative but still aligned with the user’s mental model. In a lot of ways it’s very different from a traditional taxi service but it still conforms to how a user is likely to expect a taxi service to operate. A user requests a taxi, is picked up by a car, is taken to their destination and pays the fee at the end. Elements are certainly different from a more traditional service, such as the fee being automatically deducted from the user’s account, but the service is very much aligned with the user’s mental model.

Help your users to use the intended mental model

Not only is it important to align a product or service with the user’s mental model, but also to help users to use the intended mental model. This is where the design of the mini-roundabout really failed. The design did a poor job of reinforcing the fact that this was a roundabout, leading to significant differences in the mental model employed by users.

Skeuomorphism where a digital object mimics its real-world counterpart is one way to help users to use the intended mental model. Folders, buttons, mail, wish lists, desktops, checkouts, trash cans, all real-world objects that have been utilised to help users to understand how their digital counterparts work.

Calendar and clock skeuomorphism examples
Skeuomorphism where a digital object mimics its real-world counterpart is a good way to help users to use the intended mental model

Sticking to standard design patterns and behaviours also helps users to use the intended mental model. For example, if you have a UI element that looks like a dropdown box, but behaves very differently, it’s going to lead to confusion as there is a mis-match between the behaviour and the user’s mental model.

Check alignment with your user’s mental model

A number of years ago I was working on a redesign of the checkout process for Thomson (now TUI), one of the leading holiday websites in the UK. The UX team had done lots of work to discover the user’s mental model when planning and booking a holiday. This work suggested that allowing users to configure different aspects of their holiday, such as flight times, room type and holiday activities prior to the check-out process was aligned to the user’s mental model of planning a holiday. This was what users typically did when pricing and weighing up different options. However, on user testing a design concept that allowed users to do just this it was apparent that there was a problem. Whilst the design concept fitted the user’s mental model of planning a holiday, it didn’t fit the user’s mental model of booking a holiday online. This was because it behaved quite differently from other holiday websites that forced users to select most holiday options within the checkout, rather than prior to checking out.

Checking that a design concept is aligned with the user’s mental model is very important. A great way to do this is to run usability testing (a.k.a. user testing) on the design concept. The earlier the better. Ask users to think aloud as they use a prototype of the design to carry out realistic tasks. It should very quickly become apparent where the design significantly deviates from the user’s mental model. You can even ask users what he or she expects to happen and what their expectations are prior to using the design. You can find out more about usability testing in my usability testing hints, tips and guidelines article.


Mental models are incredibly important when it comes to designing products and services that someone can use intuitively. By aligning with a user’s mental model and by helping users to use the intended mental model you can create designs that just work because users intuitively know what to do, and what to expect.

See also

Image credits

Turning the Mind Inside Out Saturday Evening Post 24 May 1941
Mini-roundabout (likely located in British Columbia, Canada) by Richard Drdul

Source link http://www.uxforthemasses.com/mental-models/


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