UX Glossary · M
Mental model
The user's internal understanding of how a system works, which is usually simpler and often wrong.
A mental model is the picture someone builds of how a system works, and uses to predict what it will do. The idea comes from Kenneth Craik’s 1943 work on how minds build small-scale models of reality; Don Norman brought it into design.
Mental models are almost always simpler than the system, frequently incorrect in detail, and entirely sufficient as long as predictions hold. Nobody knows how a lift works, and everyone can use one.
The gap that causes trouble
Problems appear when the system’s actual behaviour and the user’s model diverge at a point that matters. A user who believes closing a document saves it will lose work, and the interface, not the user, produced that belief.
This is the source of most “user error”. The user acted correctly according to a model the interface taught them.
Where models come from
Prior experience, mostly, which is why Jakob’s Law has such force. Also from the interface’s own vocabulary and structure. Calling something a “folder” imports every expectation people hold about folders, including ones your implementation does not meet.
In practice
Two options when structure and model conflict: change the structure, or change the model through labelling and feedback. Changing the structure is usually cheaper, because the model was formed over years and your product gets minutes.