Two of the many challenges people must overcome to successfully interact with technology are:
- Evaluation: Understanding the state of the system
- Execution: Taking action to accomplish a specific goal
These challenges are described as the “gulf of evaluation” and the “gulf of execution” because, without effective design elements to support users, they can become insurmountable barriers between users and their goals. Furthermore, both of these challenges are composed of subtasks which users must accomplish.
Execution and Evaluation Are Interdependent
Successful execution usually depends on correct evaluation. It was easy to formulate an action plan to use the system, but any plan based on faulty evaluation is doomed to failure.
Bridging the Gulfs with Mental Models
Interpretation requires effort, and most people try to minimize this effort by relying on a mental model to understand a system. A mental model is a theory of how a system works, what its signals mean, and what the outcomes of different user actions will be. To save time, most people rely on their past experiences to quickly build mental models for new systems. Designers can leverage this natural tendency by deliberately including design elements that help users build effective mental models.
- Identifying a relevant design which users are already familiar with
- Creating visual similarities between the new design and the familiar design
- Creating functional similarities between the new design and the familiar design
Why the Gulfs Are Important
First, the challenges of evaluation and execution transcend interaction styles and device types. Regardless of whether you’re designing for a laptop, a watch, a smart speaker, or a refrigerator, people will still have to deal with these gulfs, and this framework is flexible enough to be applied effectively to novel design contexts.
Second, when it comes to solving design problems, the granularity of breaking down evaluation and execution into specific subtasks sheds light on the detailed reasons why designs fail, because it adopts a user-centered perspective.
Users must bridge the gulfs of evaluation and execution to successfully interact with a design, but the challenge becomes much easier when the system’s creators are aware of these gulfs, and build in cues to send users down the right path.