A heuristics matrix for evaluating the learnability of safety critical medical systems

The increasing use of medical devices in non-clinical settings has elevated the importance of learnability, a key aspect of usability, that is defined as how easily users can learn to operate a system. While learnability is recognised in international usability standards, its varied definitions and inconsistent application emphasise the need for more targeted evaluation methods. This paper addresses this gap by proposing a framework for assessing learnability based on user experience levels and context of use. We define a set of user categories and introduce a learnability matrix to evaluate how different types of users, such as patients, caregivers, and medical professionals, interact with medical technologies. To illustrate the methodology, we perform a case study using the Medtronic MiniMed 770G insulin pump system. Our analysis shows that while primary and secondary users are often well-supported, passive, infrequent or adhoc users may face challenges in learning to use the device effectively in emergency settings. These findings underscore the need for more inclusive design and evaluation approaches that account for multiple user roles, to improve the safety and usability of home-based medical technologies.