A conceptual model is a mental representation of how, in a general sense, "something works". User experience guru Don Norman has defined three types of models that occur when creating an interactive application:
- Implementation models - how the application works from a technical point of view
- Conceptual models - how the designer or IA would like the user to think the application works
- Mental models - how the user thinks the application works
Conceptual modelling explained
In practise, it's hard to tease apart conceptual and mental models. A conceptual model is most often a graphic, though it can be a chart, a written paragraph or a flowchart. The key is that it expresses an explanation of the system's behaviour to the user that is easy and intuitive. Importantly, it does not have to be how the system actually works.
A mental model can be thought of as a "small-scale version" of reality that a person constructs in their mind to anticipate and predict events. Most adults carry around large numbers of mental models all the time.
Mental models can be constructed from perception, imagination, or the comprehension of language. They underlie visual images, but they can also be abstract, representing situations that cannot be visualised (e.g. a mile-high pink elephant above Big Ben).
Mental models are akin to architects' models in that their structure is analogous to the structure of the situation that they represent.
A hallmark of really good design is when the conceptual models of both designers and users are in complete agreement.