Introduction
Human factors and usability engineering is one of those specialties that most people outside medical devices have never heard of, and most people inside medical devices only fully appreciate once a use-related problem shows up in a complaint file or, worse, an adverse event report. The discipline sits at the intersection of design, risk management, and regulatory strategy: it asks whether real users, in real use environments, can operate a device safely and effectively, and it builds the evidence a regulator needs to believe the answer is yes.
For regulatory affairs professionals, human factors specialists are close collaborators rather than distant stakeholders. The usability engineering file is a required part of many device submissions, and a weak one is a common source of FDA deficiency letters and EU MDR technical documentation gaps. Understanding what this role actually does, day to day, makes it easier to work with human factors colleagues effectively and, for some regulatory professionals, points toward a natural area of specialization.
The Regulatory Foundation: IEC 62366 and FDA's Human Factors Guidance
The work of a human factors specialist is anchored in a specific, well-established regulatory framework. IEC 62366-1 is the internationally recognized standard for applying usability engineering to medical devices, and it's referenced by regulators in the US, EU, and most other major markets. FDA supplements this with its own guidance on applying human factors and usability engineering to medical devices, which lays out expectations for formative and summative usability testing, use-related risk analysis, and the structure of a usability engineering file submitted as part of a 510(k) or PMA.
What this means practically is that a human factors specialist isn't improvising a design process; they're executing a defined, auditable methodology. Use-related risk analysis identifies tasks a user must perform correctly for the device to work as intended and flags which of those tasks, if performed incorrectly, could cause harm. Formative evaluations, conducted earlier in design, explore where users struggle and why. Summative usability testing, conducted on a device representative of the final design, is the evidence that goes into the regulatory submission to demonstrate the device can be used safely by its intended users, in its intended use environment, without unacceptable risk.
A Day in the Work
On a given day, a human factors specialist might be reviewing draft instructions for use with a regulatory affairs colleague, checking whether the labeling matches what was actually validated in usability testing rather than what the engineering team originally intended to build. They might be in a planning session with design engineering, walking through a use-related risk analysis for a new device feature and arguing, sometimes forcefully, that a proposed interface change needs formative testing before it's locked.
A significant chunk of the role involves running or overseeing usability studies themselves: recruiting representative users, which for many devices means recruiting actual patients, caregivers, or clinicians rather than internal staff; designing realistic use scenarios, including simulated use errors and critical tasks; and observing, recording, and analyzing how participants actually interact with the device, instructions, and packaging. This is qualitative, careful work. A human factors specialist has to resist the temptation to coach participants toward success and instead document honestly when a task fails, because an honestly reported use error is far more valuable to the regulatory file, and to patient safety, than a flattering study that collapses under FDA scrutiny.
After a study, the specialist writes up findings and works with regulatory affairs to determine whether the results support the submission as planned or whether a design change and re-test are needed. This is often where the role becomes genuinely cross-functional: a summative test that reveals a critical use error can mean a redesign, a labeling change, or a documented risk mitigation argument, and the human factors specialist, regulatory affairs lead, and design quality engineer usually have to work through that decision together.
Where This Role Sits Organizationally
Human factors specialists are usually housed in one of a few places: a dedicated human factors or user research team, a design quality or systems engineering function, or occasionally within regulatory affairs itself at smaller companies that can't support a standalone function. Regardless of reporting line, the role works closely with regulatory affairs on every submission that includes a usability engineering file, with design and systems engineering throughout product development, and with risk management on integrating use-related risks into the broader device risk file required under ISO 14971.
At smaller medical device companies, it's common for one person to wear both the human factors and parts of the regulatory affairs hat, particularly for lower-risk devices where the usability engineering file is less extensive. At larger device manufacturers, human factors is more often a dedicated discipline with its own career ladder, usability lab space, and specialized staff who may have backgrounds in cognitive psychology, industrial design, or biomedical engineering rather than regulatory affairs itself.
Skills and Background That Lead Here
There isn't one standard entry path into human factors engineering. Some specialists come from academic backgrounds in human factors psychology, cognitive science, or industrial engineering with a specific usability or ergonomics focus. Others come from clinical backgrounds, particularly nursing or other direct patient care roles, which gives them firsthand credibility when assessing whether a device design fits real clinical workflows. Still others move into the role from design quality or systems engineering within a device company, picking up usability engineering expertise through IEC 62366 and FDA guidance study and on-the-job experience running studies.
For regulatory affairs professionals specifically considering this as an adjacent specialization, the most useful preparation is hands-on familiarity with how usability engineering files get built and reviewed, which often starts with working closely alongside a human factors team on a few submissions before attempting a lateral move. Strong written communication matters more than people expect, since usability engineering reports and risk analyses need to be clear enough for an FDA reviewer with no prior context to follow the reasoning from identified use-related risk through to validated mitigation.
Common Friction Points With Regulatory Affairs
Because human factors and regulatory affairs work so closely together, a few recurring friction points are worth naming plainly. One is timing: usability engineering, done well, takes real calendar time, and summative testing in particular can't be meaningfully compressed without undermining the quality of the evidence. Regulatory affairs professionals who build submission timelines without consulting their human factors colleagues early risk discovering, late in the process, that a critical task failure requires a design change and a repeat study, pushing the submission date back by months rather than weeks.
Another is scope creep in the use-related risk analysis. It's tempting, especially under deadline pressure, to narrow the list of critical tasks or the range of user groups tested in order to simplify the study and shorten the timeline. A rigorous human factors specialist will resist this, because a usability engineering file that conveniently avoids testing a user group or task likely to reveal problems is exactly the kind of gap an FDA reviewer, or a post-market adverse event, is likely to expose. The best working relationships between regulatory affairs and human factors treat this tension honestly rather than letting regulatory timeline pressure quietly erode the rigor of the usability program.
A third friction point is translating study results into submission language. Regulatory affairs professionals are often the ones who have to take a human factors report, with its qualitative observations and use-error taxonomy, and build it into a coherent regulatory narrative that connects identified risks to specific mitigations and residual risk justifications. Doing this well requires regulatory affairs to actually understand the human factors methodology well enough to represent it accurately, not just extract a pass or fail conclusion.
Certification and Professional Development
Unlike regulatory affairs, which has a well-known certification in the Regulatory Affairs Certification from RAPS, human factors engineering doesn't have a single dominant credential specific to medical devices. The Board of Certified Professional Ergonomists offers a broader human factors and ergonomics certification that some specialists in this field hold, and professional involvement with the Human Factors and Ergonomics Society is common among people doing this work seriously. For medical device-specific grounding, direct study of IEC 62366-1 and FDA's human factors guidance, along with attending AAMI or RAPS sessions focused on usability engineering, tends to be more directly useful than pursuing a general ergonomics credential alone.
For someone building toward this specialty from a regulatory affairs or design quality background, the most credible way to develop real expertise is still participation: sitting in on usability studies as an observer, co-authoring use-related risk analyses, and reviewing FDA deficiency letters related to human factors deficiencies to understand what reviewers actually flag as inadequate. There's no substitute for having watched a real user struggle with a real device interface to understand why this discipline exists.
Conclusion
Human factors and usability engineering is a discipline built on a simple but demanding premise: a device that works perfectly on a lab bench is worthless if a real user, under real conditions, can't operate it safely. The specialists who do this work translate that premise into rigorous, standards-based evidence that regulators can evaluate and trust. For regulatory affairs professionals, understanding this role well enough to collaborate on it effectively, and in some cases to grow into it directly, is an increasingly valuable piece of medical device regulatory literacy.