Mental Models in HCI

Mental models are internal representations with which users understand, predict and operate systems. They play a central role in human-computer interaction (HCI).

Definition

A mental model is a simplified, subjective idea of how a system works. It influences how people interact with this system.

Why mental models are crucial

When people use a new system, they build on experience and analogies. Mental models help them to explain functions, predict actions and avoid problems - for example when exploring an unfamiliar interface.
If this model is missing, users feel disoriented. If it is wrong, frustration arises: for example, when the “Save” button does not do what was expected.

Mental model vs. system model

The famous triad in the HCI is:

system model - how the system actually works technically
Designer model - how developers think the system works
Mental Model - how users believe it works

Problems arise when the user’s mental model does not match the system model - a classic example: the recycle bin icon on the desktop suggests complete deletion. In reality, the file is only moved - a misunderstanding that UX design must correct.

Best Practice Example

Users often believe that a “Send” button in an app sends a message immediately - even though it is first cached locally. A loading animation or feedback message can help to make the mental model more realistic.

How design supports mental models

A good interface conveys functions intuitively. This is achieved through:

Consistency - e.g. similar navigation as in known apps
Affordances - such as buttons that look like real keys
metaphors - such as “desktop”, “folder”, “recycle bin” or “shopping cart”
feedback - for example through animations, sounds or status displays
Error tolerance - e.g. “Undo” function or warnings before deletion

You can find out more about affordances here.

How to capture mental models

UX research uses various methods to make mental models visible:

Card Sorting shows how users structure information.
Interviews and Thinking-Aloud-Methods provide insight into thought processes.
Concept Mapping visualizes explicit ideas.
The ** comparison of user behavior with system logic** uncovers model conflicts.

These methods are closely linked to the pages on the Thinking-Aloud-Method and UX-Interviews.

Conclusion

Mental models are cognitive tools that we use to understand the digital world.
A user-centered design takes into account not only how a system works - but also how it is understood.
Because the better the system logic and mental models match, the more intuitive the use becomes.

Take Home Message

Systems should adapt to the user’s mental model - not the other way around.

Last modified: 17 June 2025