Person thinking about a book


What is a mental model? – The term mental model has been around for at least the last 25 years. One of my favorite definitions is from Susan Carey’s 1986 journal article, “Cognitive science and science education”, which says:



Users create mental models very quickly — often before they even use a website or a product. Users’ mental models come from their prior experience with similar sites or products, assumptions they have, things they’ve heard others say, and also from their direct experience with the product or device. Mental models are subject to change.


Mental models vs. conceptual models – In order to understand why mental models are so important to design, you have to also understand what a conceptual model is and how it is different from a mental model. A mental model is the representation that a person has in their minds about the object they are interacting with. A conceptual model is the actual model that is given to the person through the design and interface of the actual product. Going back to the iPad ebook example, you have a mental model about what reading a book will be like in the iPad, how it will work, what you can do with it. But when you sit down with the iPad, the “system” (the iPad) will display what the conceptual model of the book app actually is. There will be screens, and buttons, and things that happen. The actual interface is the conceptual model. Someone designed an interface and that interface is communicating to you the conceptual model of the product.

Why care about this mental model/conceptual model idea? –Here’s why you should care: If there is a mismatch, between the person’s mental model and the product’s conceptual model, then the product or website will be hard to learn, hard to use, or not accepted. How do mismatches occur? Here are some examples:

  • The designers thought they knew who would be using the interface and how much experience they had with interfaces like this, and they designed according to those assumptions without testing them, and it turns out their assumptions were wrong.
  • The audience or the product or website is varied. The designers designed for one “persona” or type of audience, and the mental model and conceptual model match for that group, but not for others.
  • There are no real designers. The conceptual model wasn’t really designed at all, It’s just a reflection of the underlying hardware or software or database. So the only people whose mental model it fits are the programmers. If the audience is not the programmers then you are in trouble.

What if the mental models the users have won’t work? — What if it’s a brand new concept and you don’t want to match the current mental model? – What about the idea that people who have only read real, physical books will not have an accurate mental model of reading books on the iPad? In this case you know that people will not have an accurate mental model that fits. You will need to change their mental model. The best way to change a mental model is through training. You can use a short training video to change the mental model before the iPad even arrives at their door. In fact, one of the best purposes of training on a new product is to adjust the audiences’ mental model to fit the conceptual model of the product.

A different use of the term – By the way, the way I’m using the term mental model is, I believe, the most common definition, but it does not fit with at least one of the new definitions I’ve been reading and hearing about lately. Indi Young has written a book called Mental Models, and she’s using the term in a different way. She diagrams the behavior of a particular audience doing a series of tasks, including their goals and motivations. Then underneath that she describes what the “system” or product will do, or be like, in order to match the task. This entire structure she calls a “mental model.” Her methodology and its output look useful, but it doesn’t match the definition of mental models that I’m using here.

The Best Designers – a) understand the mental models of the intended audience (with task analysis, observations, interviews, etc), and  b) design a conceptual model to fit the audience’s mental model, or a design a new one and know how to get us to switch from old to new.

Take Aways:

  • People always have a mental model, and it often doesn’t match what the conceptual model that someone designed (or forgot to design!).
  • The secret to designing an intuitive and delightful product experience is making sure that the conceptual model of the product matches, as much as possible, the mental models of your audience.
  • If you have a brand new product that you know will not match anyone’s mental model then you will have to provide training to prepare the person to create a new mental model.
  • If you are struggling to learn how to use a new website, software or device, it might be because you are holding on to an old mental model that doesn’t work anymore. Try letting it go and looking at the product without so many assumptions about how it works.

What do you think? What products have you had a hard time with because your mental model didn’t match the conceptual model? If you are a designer, what do you do to try and get a better match?