One of the best parts of my job as a human factors researcher is interacting with participants during studies. Early medical device studies generally have bare-bones definitions of intended user groups that become more defined throughout the product development life cycle, but every time, even the vaguely defined users on paper come alive when they show up in person.

It can be easy to imagine a medical device’s users as the shapeless, homogenous groups that appear on paper. When you think “patients aged 18-65” or “pediatric nurses with at least 6 months of experience,” it’s natural for a single representative character to pop into your head to symbolize the entire group. In fact, the practice can be helpful, as demonstrated by the role of personas in design thinking and product research.

When left unchecked, however, these characters can warp into one “average” or “ideal” user depiction that does not actually exist. Worse still, these generalizations can perpetuate stereotypes about a particular user group that result in a product that only meets the needs of a narrow slice of users, if any at all. Failing to generate representative user needs can be a sure way to marginalize disadvantaged users based on their race, gender, disability, or sexuality.

Among users of medical devices, there is arguably no better demographic to speak to about the dangers of assumptions than the disability community. One in four Americans identify as having a disability, which does not even include undiagnosed disabilities or disabilities related to aging. Disabled people have unique and often extensive perspectives of healthcare that are underrepresented in medical research, even though they are one of the greatest potential beneficiaries of health innovations. When we intentionally seek out disabled users, not only do we collect more data, but we also enrich the quality of our research, which makes for better insights.

As human factors researchers, we are tasked with evaluating medical devices based on their real-world use, which prompts us to account for disability in two ways:

1. 1. 1. 1. Ensuring that the device accommodates users with diverse abilities to the greatest reasonable extent, and
         2. Evaluating the device for its ability to accommodate users with disabilities in context of their disability.

We suggest the three questions below to start the process of incorporating users with disabilities into your research:

What abilities are required to use this product?

When preparing for late-stage medical device studies, we break down every interaction a user has with a medical device into discrete tasks in a process known as task analysis. We ask ourselves what stimuli a user must perceive, what information they must process, and what actions they must take to successfully complete each task, which all comes down to the user’s levels of ability.

When evaluating a medical device’s usability, we use our task analysis to consider how and for whom the device may fall short of meeting user needs during critical tasks. Is there a situation or environment where hearing a critical alarm may be less likely? If so, can we add another mode of feedback to complement the alarm, such as a visual alert or a vibration? How likely is it that users may be distracted by a different task when this alarm could sound? When we ask these questions, we are assessing the limits of human performance for all users, not just those with permanent limitations. With this approach, we have a more robust method for assessing use-related risk and are also considering the needs of users with disabilities by design.

Does our product empower disabled users?

One of the core beliefs of usability is that products exist for the people who use them. This is a simple idea, but in practice, it’s not so easy to achieve. For example, think about one terrible product you have used recently. Maybe it’s a kitchen appliance, a new gadget, or a website. What was it like to use it? What frustrated you about it? How many tries did it take you to use it successfully? Bad products are everywhere because the people making them can unintentionally lose sight of the people using them.

It’s all too easy – in fact, it’s very human – to unconsciously reduce the complexities of a product’s user population into one generalized “average” user. This average user has the capabilities to do everything needed for normal use: obtain the product, open the package, read the instructions, and perform every step with overall success in a neutral environment. Unfortunately, this average-user schema misses out on the diversity of real-world users. When assumptions are left unchecked, it’s easy to assume that any deviance from the average is an abnormality or even a failure on part of the user.

This becomes obvious when we observe experiences of the disability community in the healthcare system. It’s undeniable that medical innovations have significantly improved the quality of life for disabled people, but it’s also true that users with disabilities are frequently treated as a “deviance” from the normal and their disabilities as something that needs to be “fixed.” This systematic marginalization of disabled people is referred to as the medical model of disability, which is the perception that disability exists in a person’s body and must be “fixed” with medical intervention.

If we’re not careful, we can perpetuate the medical model by attributing observed use-related issues to users’ lack of ability. Not only does this inappropriately place the blame of the failures of the device on disabled users, but it also obscures the failures of the device to meet user needs, resulting in unreliable research and faulty root causes. In response, we must adopt what disability activists refer to as the social model of disability, which shifts the blame away from individuals and towards the social and environmental factors that fail to accommodate them. By focusing on the device instead of users’ limitations, we can identify where our device fails to meet users’ needs and respond accordingly.

How do we ensure accessible testing?

A common slogan in the disability rights movement is “nothing about us without us.” In human factors research, we can incorporate this idea by considering disabled users to be development partners rather than of mere beneficiaries of medical devices. Disabled users are not limited to patient groups: they are also caregivers, healthcare providers, engineers, and technicians.

Including disabled people early and often throughout product development makes for better experience for all users. Intentionally recruiting from the outer margins of user groups can aid in defining the performance-related limits of user populations as well as collect invaluable insights from disabled users. Testing with users who may require additional accommodations also increases the likelihood of exposing a device’s weak points earlier in testing. This leads to a better product and faster design optimization, making for a greater return on investment from usability testing.

Excluding participants with disabilities can be explicit (i.e., screening out participants with physical or cognitive impairments), but it can also occur unintentionally because of implicitly biased questions or advertising methods. Participants with disabilities may be less likely to meet common requirements for study participation, such as internet connection, reliable access to transportation, and medical literacy. users are also more likely to be located at intersections of other marginalized identities due to race, class, or gender that present even more systemic barriers to healthcare access. At a minimum, ensure that disabled participant groups, especially those that may be relevant to device use based on its use-related risk analysis, are not screened out during recruiting. To go further, ensure that individuals in the disability community are intentionally included in human factors testing to assess how a new design accommodates, or fails to accommodate, their capabilities and limitations.