How well do you understand your customers? Do you know how they make decisions? How they see your business’s domain? What makes them tick?

Everyone understands things a bit differently. Nobody has a perfect, complete understanding of the whole of reality. A neurosurgeon may understand the human nervous system but be unable to successfully configure the security settings of her smartphone. Knowledge of one domain doesn’t necessarily translate to another.

You carry around in your mind internal representations of how things work. These representations are called mental models. Wikipedia has a “good enough” definition:

A mental model is an explanation of someone’s thought process about how something works in the real world. It is a representation of the surrounding world, the relationships between its various parts and a person’s intuitive perception about his or her own acts and their consequences.

The more accurately these representations mirror the way things really are, the more skillfully you can act. If you understand the distinctions between the components that define your phone’s security and how they relate to each other, you’ll be able to make good predictions about the consequences of your decisions.

Forming good mental models for complex domains isn’t easy. Modeling calls for thinking in abstract terms. You may be tempted to apply a model from one domain you understand well to another you don’t. (E.g., “I bet this works just like x.”) We aren’t formally trained to model the world. Instead, we form mental representations ad hoc, filling out the broader picture as we go along. Thus, we have imperfect models of much of reality.

Ideally, you want your customers to have good mental models of your business’ domain. This is easier to do in well established domains than in new ones. For example, more people are likely to have good mental models of the process of renting a car than securing their smartphone.

It’s important that you understand your customers’ mental models for your domain. This isn’t something you can ask them about in an interview. We don’t express our mental models overtly. Instead, they manifest indirectly in our actions. What to do?

One way to go about it is to observe them interacting with prototypes and making note of how they interpret its major concepts and their relations to each other. Another is to engage customers in co-creation sessions to design solutions for the domain.

In this second approach, we don’t expect the solutions that emerge to lead directly to products or features. Instead, the artifact functions as a MacGuffin that allows us to map the customers’ mental models of the domain. This approach is especially useful in early stages of the design process, when we don’t yet have a prototype to test.

With a better understanding of how customers see the domain, we can design solutions that allow them to make more skillful decisions. This may call for producing means for them to adjust their mental models to more closely align to reality. Or it may require that we adjust the system we’re designing to better match the models users bring with them.

In either case, we’re not starting from a blank slate: we must meet people’s understanding of the domain. This requires that we understand their mental models.