Conceptual Model

A simplified explanation of how something works that lets a person predict its behavior. The designer holds a design model, the user forms a mental model, and the two communicate only through the system image: what the artifact actually presents.

Why it Matters

When the system image conveys a clear conceptual model, users understand and predict the system. When it does not, users invent their own model, usually wrong, and are repeatedly surprised.

Signals

• Users hold incorrect theories about how it works ("I thought it would do X").
• Behavior seems magical, arbitrary, or unpredictable.

Benefits

Predictability, easier learning, and graceful handling of new situations by reasoning from the model.

Risks

An unclear or absent system image; a designer's model that never reaches the user; exposing the implementation model instead of a usable one.

Tensions

A simpler conceptual model is easier to learn but may hide capability; the truest model (the implementation) is often the least usable.

Examples

The desktop "files and folders" metaphor; a thermostat understood as a target temperature rather than a valve; a trash can that conveys "deleted but recoverable."