Mental model diagrams depict the steps involved in a task procedure and indicate how users are supported by the website or application at every step. The diagram may be divided into two halves; the top half represents the user’s mental model, and the bottom half represents how each task is supported by the system. Mental model diagrams are useful for developing the task flow of a system and for identifying gaps where a system design does not fully support its users.

The User’s Mental Model

The top half, or the user’s mental model, describes the task procedure in terms of mental spaces, conceptual groups, and atomic tasks.

Mental spaces are high-level goals, such as, “Get Ready for Work.” Within a mental space, there may be several conceptual groups, which are groups of tasks that need to be done in order to accomplish the goal. Conceptual groups for the mental space, “Get Ready for Work,” may include: “Get Dressed,” “Eat Breakfast,” and “Watch the Morning News.” Each conceptual group contains more specific, atomic tasks. For example, in order to “Get Dressed,” you may need to get out of bed, shower, brush your teeth, style your hair, and choose clothes to wear.

The diagram shows atomic tasks stacked into a tower shape, which becomes a conceptual group. Multiple towers of conceptual groups become a mental space. Mental spaces are divided by vertical lines and are depicted in the order in which they are chronologically carried out. The mental space “Get Ready for Work” may be followed by the mental space, “Work,” which may be followed by “Return Home,” and finally, “Spend Time with Family.”

Supporting System Features

Below each tower, or conceptual group, is another stack of boxes that indicate the various features or system tools that support the tasks in the conceptual group. For example, for the conceptual group, “Get Dressed,” people may use the following tools to get dressed: a toothbrush, soap, shampoo, a hairdryer, a brush, hair styling products, a closet, and clothing.

If there is an atomic task that the system does not currently support (in other words, no feature has been created to help users accomplish the task), you can indicate this in the bottom half of the diagram by creating a different-colored box and listing a new feature concept that could support that task. When creating new feature ideas, it is best to base them on user needs and preferences. In fact, it’s likely that users will tell user researchers about these “gaps” in surveys, interviews, and focus groups, and during user observations in the form of user-created workarounds.