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By Naomi Cherne

If you are reading this blog, you are probably pretty comfortable with reading. You can engage with the text in your world to understand and evaluate your options, guide your actions, and pursue your goals. However, literacy is a struggle or even a barrier for lots of people. If your medical device requires that people use text in any form, then you should consider the literacy of your user groups when thinking about usability.

  • 35% of adults in the US have limited health literacy
  • 44% of high school graduates and 76% who did not complete high school have limited health literacy
  • 17% of adults in the US cannot draw low-level inferences from text
  • 50% of adults in the US cannot integrate, interpret, or synthesize information from complex texts
  • 69% of adults in the US who did not complete high school are at or below the lowest level of literacy proficiency

In our experience, literacy can affect someone’s product interactions in many ways. For example, one subtle impact is that a product’s first impression can have a stronger influence on use across the entire interaction. People bring with them a set of expectations and an eye for affordances; written materials provide an opportunity for people to move past incorrect assumptions about how a product should be used. People who have low literacy may not engage effectively, or at all, with written materials, and may become fixed in their first impressions. Testing your product with low literacy participants can help reveal problematic first impressions as well as what parts of the written materials are ineffective for those participants.

The FDA notes that literacy could affect someone’s ability to use a medical device, and suggests considering the literacy levels of the people who use your product, as well as the level of education and health literacy regarding the relevant medical condition(s). The FDA also states that human factors testing of the product should include participants with these literacy levels if it is expected that literacy could influence how they interact with the product.

People with limited health literacy may not know medical terms, or know how to interpret test results, and may have trouble communicating with their healthcare providers and struggle to find and follow information in written materials. Written materials are not limited to words on a page or on a sticker. Do your users have to follow legends on a graph or labels on a diagram? Do they have to click their way through hyperlinked text of web pages to learn information or do tasks? Written materials include the paragraphs, sentences, diagrams, labels, charts, hyperlinks, and abbreviations in your electronic and printed instructions for use and labeling. If your product requires that the people who use it read labels and instructions, then you care about literacy.