It is important that medical product designers not make assumptions about users. What might be obvious to you as the designer might not be obvious to those using what you’ve designed. People will always make mistakes. It’s impossible to design a perfectly fail-safe system. The approach to take is to anticipate as much as possible the mistakes that people might make and design those mistakes out. Just because your device has a loud alarm when it goes into fault mode doesn’t mean that users will necessarily pay attention to it, especially if the alarm occurs on a repeatable basis. We habituate to regularly recurring signals. In an operating room, personnel can easily become overburdened by alarms on numerous devices, to the point that the alarms are ignored. Further, how difficult it is to grab people’s attention depends on how engrossed or involved they are. If someone is concentrating on a particular task, they are probably filtering out a lot of information. Performing a failure modes and effects analysis (FMEA) is one way of identifying cognitive errors that users could make. Indeed, FMEA or similar procedures are required for medical devices as part of the FDA’s design control regulations.