How do you design a usability test that mimics the panicked, stressful situation that a user may be in when he or she is using your medical device in the real world?

T. Grant Leffingwell

Imagine you are manufacturing a handheld combination product, designed to be used in a very rare "rescue" type of scenario. You need to test this product with users but you don't know how to do it in a way that provides insight into how it will be used once it's on the market. How do you design a usability test that mimics the panicked, stressful situation that a user may be in when he or she is using your device in the real world?

Regulations released by FDA in February 2016 ("Applying Human Factors and Usability Engineering to Medical Devices") states that, "the conditions under which simulated-use testing is conducted should be sufficiently realistic so that the results of the testing are generalizable to actual use." This guidance creates a challenging problem for manufacturers. How do you conduct a "sufficiently realistic" usability test of a device that is intended to be used under stressful conditions? After all, since usability test participants are recruited, screened, consented, and prepped for your test session, it's not like you can surprise them with a novel situation that they would ordinarily be unprepared for.

Fortunately, there are approaches that can be used to ensure that you can collect meaningful observational data on how your product might be used in a stressful scenario. These techniques take advantage of some common ways humans experience various forms of stress.

For starters, the best way to induce stress for a controlled study is to begin with as much realism as you can reasonably and ethically recreate. For the above example of a handheld rescue device, perhaps that means having a mannequin on the floor, appearing as if it has just collapsed.

Another thing to consider is the type of stress that you expect your users to be experiencing when using the product. The stressor could be largely cognitive, where a great deal of attention and focus is required on the part of the user. In that case, you might use a technique like time pressure: instruct the participant to complete the task as quickly and accurately as they can, and tell he or she that they will be timed. Another technique is to give them a high cognitive load, burdening them with unnecessary information to keep in mind as they perform the scenario. Distractions are also useful--perhaps at a strategic moment during the scenario, you could distract the participant to divert their attention elsewhere.

Conversely, the stressor may be that the device requires high dexterity to operate properly and could be affected by someone's sweaty and/or shaking hands. In this case, you could work into your scenario an excuse for your participants to undergo a little physical stress.

We should refrain from exerting too much stress on the subjects. Excessive intensity, stress, or realism simply isn't ethical. It's important to find a balance. Always make sure you're involving an institutional review board (IRB) for studies with stress scenarios to help ensure that the rights and well-being of your participants are protected.

T. Grant Leffingwell is principal usability researcher for human centric design at Battelle.

[Image courtesy of GERALT/PIXABAY]