We have all been there. Struggling with a TV remote full of buttons, not knowing which one does what. Or getting lost on a confusing website and spending minutes just to complete a simple task. These moments are annoying, and we usually blame ourselves, thinking, “How could I not figure this out?”
Now imagine the same confusion on the screen of an infusion pump, where an intensive care nurse is trying to set the correct dose of a life-saving drug. In this situation, a moment of hesitation or a single wrong touch is not just frustrating—it can be fatal.
In this article, using the medical device safety standard ISO 62366-1 as a starting point, we will look at four powerful and thought-provoking lessons. These lessons are not only valid for medical devices, but for all products we use every day.
1. The Myth of “User Error”
The concept of “user error” is a dangerous myth. In most cases, the real source of the error is not the user, but the product design. ISO 62366-1 takes a very clear position on this and shifts the focus from the user directly to the design. The core message of the standard is simple:
“Use errors are most often the direct result of poor user interface design.”
This mindset does not aim to create “error-free users.” Instead, it accepts that humans make mistakes and focuses on designing systems that minimize the harm caused by those mistakes.
This principle is not limited to life-saving devices. Think about a simple money transfer screen in a banking app you use every day. Imagine the “Send” button and the “Add New Recipient” button placed next to each other, in the same color. If you tap the wrong one while distracted, is that really your fault—or is it a design that invites errors?
2. “Normal Use” Is Not What You Think: Errors Are Part of the Game
When we hear “normal use,” most of us imagine using a device perfectly and exactly as instructed. ISO 62366-1 radically expands this definition. According to the standard, NORMAL USE includes two situations:
- Correct use: Using the device without errors.
- Use error: Using the device with foreseeable mistakes.
The most surprising part is that designers and manufacturers are required to treat foreseeable user errors as a natural part of use. This responsibility clearly lies with the product development teams.
3. The Safest Design Is the One That Does Not Need Warnings
Many products try to solve design weaknesses and risks with warning labels or long instructions. This is often a form of “design shortcut” that shifts responsibility to the user. ISO 62366-1 strongly rejects this approach and defines a strict priority order for risk control:
- Inherently safe design: Solutions that eliminate the risk from the start.
- Protective measures: Physical or technical measures, such as alarms.
- Information and warnings: The last resort.
A clear example is connectors that cannot be connected incorrectly. If you design incompatible connectors, you eliminate the risk of a wrong connection entirely. This is inherently safe design—no warnings needed.
A well-designed connector does not need a “this side up” label. In the digital world, when we fail to achieve this level of safety, we see constant pop-up help bubbles. If software needs help bubbles to explain what a feature does, this is not really help—it is a confession. The designer is essentially saying, “I could not make this interface self-explanatory.”
Of course, adding a help bubble with a few lines of code is faster and cheaper than redesigning a complex interface. It is easy to see why this option is tempting. However, the standard warns us clearly: the short-term time savings are unacceptable when compared to the long-term costs of user frustration, increased support requests, and damage to brand reputation.
4. Usability Is Not Luck—It Is an Insurance Policy
There is a common belief that intuitive and user-friendly products are created simply through “common sense” and good aesthetics. ISO 62366-1 says otherwise. Safe and usable products are not created by chance; they are built through a structured Usability Engineering Process.
When project timelines are tight, usability activities are often seen as a “luxury” or a “waste of time” and are the first to be cut. This mindset is fundamentally wrong.
This process is not a cost. It is an insurance policy that prevents much more expensive and damaging problems later. Early in my career, I clearly remember a project where we skipped this insurance because “we did not have time.” The result? For six months after launch, we spent our days in emergency meetings, fixing one critical issue after another. The price of not having that insurance was at least ten times higher.
Conclusion: From Blame to Responsibility
The lessons from medical device design show us that effective and safe design does not expect users to behave perfectly. Instead, it takes human fallibility into account.
So next time you encounter a “user error,” what will you think? Will you blame the user, or will you question the design?
Let us see this question not as an ending, but as a starting point. The answer depends on the role you play—and every role has the power to break this cycle.
For Designers: Change the question in your next project. Instead of asking, “What if the user misunderstands this?”, ask, “How can I make this interface impossible to misunderstand?” Eliminate risk through design, not warnings.
For Product Managers: Present usability testing not as a cost item, but as an insurance policy for project success. Remember: every 1 unit invested at the beginning can save you 10 units spent fixing problems after launch.
For End Users: When you struggle with an application, remind yourself: this is not an intelligence test. The problem is not you—it is the product. And remember, every time you stay silent, you allow bad designs to remain part of our lives.
Responsibility belongs to all of us.
