Maximising design consistency and existing mental models to take advantage of 'positive transfer'

This article was written in collaboration by Jenny Collinson, Director of Human Factors Strategy & Advisory and Fabiana Lombardi, PhD, Human Factors Consultant at ClariMed.

In the world of healthcare, precision and efficiency are paramount. For some medical devices every second counts, and decisions can have life-altering consequences. This is why the user interface (UI) design of medical devices isn't just a matter of aesthetics; it's critical to ensure safe, effective use for individuals.

In Human Factors, we talk a lot about negative transfer – how someone's prior experience has negatively impacted their interactions with a device, but we hear less about "positive transfer," which refers to a situation where prior learning or experience facilitates performance in a new, related task or environment. Essentially, it's when what you have learned before helps you do something new more effectively.

Positive transfer occurs when similarities between the old and new situations allow for the application of existing knowledge and skills.

• It can lead to faster learning, improved performance, and reduced errors.

• In human factors, positive transfer is crucial for designing user-friendly systems and interfaces.

• The goal is to leverage users' existing mental models and expectations to make new systems feel intuitive.

For example: If a new software program uses similar icons and menu layouts as a familiar program, users will experience positive transfer, and their prior experience will help them navigate and use the new software more easily.

Ultimately enabling positive transfer is a key objective in UI design. By ensuring people can transfer their prior learning, we can create systems that are:

• Easier to learn.

• More efficient to use.

• Less prone to errors.

In essence, positive transfer is about designing systems that "play to" people's existing knowledge and skills, making them more effective and user-friendly.

One of the most powerful design tools we can utilize to maximize positive transfer is design consistency. A consistent UI across a range of devices, similar product types or even within a single complex machine, offers a multitude of benefits, contributing to better usability outcomes and a smoother workflow for healthcare professionals.

What are the benefits of UI consistency?

• Reduced cognitive load and errors: Consistency of layout and user interactions reduces cognitive load, allowing more focus on the clinical task. This minimizes the opportunity for error and delay.

• Minimization of training requirement and improved adoption: Training can be simpler and more efficient – reducing the learning curve for new devices. Devices will seem intuitive and easy to use and therefore be more easily introduced to workflow.

• Improved user safety: Clear and consistent designs minimize use error, increases efficiency and improves overall user experience

• Brand recognition and trust: Consistency across product platforms increases brand recognition and builds confidence in the brand.

So... how can we achieve consistency?

There are several ways in which we can aim to build in our existing knowledge to ensure consistency of design.

• Establish clear design guidelines and style guides.

• Conduct thorough user research and evaluations.

• Prioritize usability and accessibility.

• Maintain open lines of communication with end users.

• Employ standardized design elements and interaction patterns.

Another tool that can be utilized is to take advantage of users' existing mental models.

In Human Factors, mental models are referred to as a set of knowledge, beliefs, expectations and experiences that a person has about the world, and in particular, about a system or a device. People will utilize their mental models to interpret and understand external information. They will then, based on the comparison between their mental model and the external information, form predictions about the system of the device and plan their sequence of actions accordingly.

When designing a medical device, ensuring that the device follows an established behavior, interaction pattern and fitting with users existing knowledge and understanding, should be central for the successful outcome of that interaction. In other words, the sequence of actions used to interact with the device should not only reflect users' mental models, but it should match it as accurately as possible.

For this reason, mental models should not just be seen and utilized as root causes for potential use errors, but instead they should be used as guidance during the designing process.

From a psychological perspective, mental models can be described as internal representations of some domain or situation that supports people's understanding, reasoning, and prediction. They also permit reasoning about situations that might not be directly experienced. Ultimately, they allow people to mentally simulate behaviors based on previous interactions.

To better understand what internal representations are, and how can be useful for successful design, let us imagine this scenario: "You have been invited to a friends' BBQ, and while your friends are welcoming more guests you have been given the very important duty of checking the meat that is on the BBQ. It should be an easy task, until you remember that your friends are BBQ experts and have all BBQ utensils that look like very high-tech tools. You look at the meat on the grill and look at the tongs that you are supposed to use. What are those? You have never seen tongs like that in your life! They look like giant scissors… that's it! You know how to use scissors, so by pretending to use them as if they were scissors everything should be fine. You were right! The meat is perfectly cooked, everyone is happy and enjoying their food, and you have been crowned the BBQ Tong Expert!"

Throughout the course of our lives, we experience different kinds of objects and have the ability to extract the features that characterize them. This represents the foundation of our mental models, and how these can be used to direct perceptions, cognition, and actions. As presented in the example above, people's ability to utilize their existing mental models and to adapt them to their current situational needs, should be considered as a powerful way to achieve optimal usability.

Want to learn more about building positive transfer into the design of your medical device UI?

Our human factors experts can help you implement these principles to create intuitive, efficient, and error-resistant interfaces that leverage your users' existing mental models. Whether you're developing a new medical device or improving an existing one, we can guide you through the process of designing for positive transfer to enhance usability and individual safety.

Contact us today to discuss how we can help optimize your medical device UI design and ensure regulatory compliance while creating exceptional user experiences.