What are Mental Models, Anyway?

Anyone with a cursory familiarity with User Experience (UX) has stumbled across the term mental models. But what does the term mean? It sounds a bit like jargon. However, mental models are not a trendy buzzword. They were introduced in 1943 by psychologist Kenneth Craik, who proposed that people carried a small-scale model of how the world works in their minds. The models are used to anticipate events and form explanations.

“Mental models are cognitive representations of external reality” (Jones, Ross, Lynam, Perez, & Leitch, 2011).  Representations is the keyword. Mental models are not facts. They are beliefs—in UX—about a system (e.g., a website or an application). The UX designers bank that user mental models are similar to (or grounded in) reality.

Jakob Nielsen, a co-founder of the Nielsen Norman Group, explains users “base their predictions about the system on their mental models and thus plan their future actions based on how that model predicts the appropriate course.” Of course, every person’s mental model differs from the next. This includes designers.

The graphic on the top of this post depicts the relationship between the designer’s mental model and the user’s mental model. It is based on a diagram and idea created by Donald Norman (the other co-founder of Nielsen Norman Group) and first appeared in Norman & Draper’s User Centered System Design (1986).  It is a triad: “The designer’s model, the system image, and the user’s model. For people to use a product successfully, they must have the same mental model (the user’s model) as that of the designer (the designer’s model). But the designer only talks to the user via the product itself, so the entire communication must take place through the ‘system image’: the information conveyed by the physical product itself” (Norman, 2008).

Usability problems occur when the user’s mental model doesn’t harmonize with (or follow) the designer’s mental model. Fortunately, mental models are not static. They are fluid and evolve as people gain experiences.  Nielsen warns that more than just experience with a system affects users’ mental models. Users’ mental models are affected by outside sources, like talking to other users and applying what they’ve learned from other systems.

Understandably, users form their mental models based on previous interactions with applications and websites. Users anticipate functionality in user interfaces (UI) to be consistent with their past experiences. If an interface doesn’t follow convention, there is the potential for conflict or confusion.

According to Nielsen, type-in boxes are a common source of confusion. If a website includes multiple search features on the same page, users often can’t tell them apart. Windows are another sticking point for users. Users have trouble distinguishing an operating system window with a browser window. And, windows are regularly confused with applications.

Changing users’ mental models is difficult because designers have to overcome an established user understanding. In most cases, it’s best to adjust the user interface to follow users’ mental models. If designers need to improve users’ mental models, they need to tell users stories.

Conceptual Models

People are anecdotal by nature. We learn from stories, not logic. According to Norman, conceptual models are the method designers can use to improve users’ mental models. “What are conceptual models? I think the easiest way to conceive of them is as stories, stories in context. A model is a story that puts the operation of the system into context: it weaves together all of the essential components, providing a framework, a context, and reasons for understanding” (Norman, 2008).

Mental models are users’ representations (or beliefs) about a system and are critical for UX designers to grasp. Without an understanding of users’ mental models, confusion will plague a user interface.

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