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By Scott Walters, Ph.D., and Dana Litt, Ph.D., Department of Health Behavior and Health Systems, School of Public Health, University of North Texas Health Science Center

An old Saturday Night Live sketch has Will Ferrell playing a man with “voice immodulation syndrome,” a condition that prevents him from controlling the pitch or volume of his voice. Whether he’s trying to comfort a baby, whispering in church, or muttering to himself about how poorly the interviewer is doing, it’s the same obnoxious volume. It makes for an awkward—and hilarious—interview.

One of the special challenges in public health is finding the right tone or pitch to convey the right message at the right time. People want clear, consistent messages about what to expect and how to act. However, health risks are sometimes complicated and can change as new information becomes available. People also tend to be poor at estimating risk and adjusting behavior in response to new information. For example, people tend to overestimate the probability of rare, serious events and underestimate the probability of more common, but less serious events.

People may also come to dramatically different conclusions when the same information is presented in slightly different ways. So how can public health professionals accurately convey risk—in particular, when recommendations need to be changed? Poorly communicated, it may appear to some people that public health messages can’t be trusted at all.

Below are some strategies that can help convey risk (and changing risk) over time:

• Choose risk categories that are simple, meaningful, and clearly connected to data. With qualitative categories, people might be told there is a “low,” “medium” or “high” chance of something happening. Color schemes, happy/sad faces, or up/down arrows can be used to convey categorical risk. Quantitative categories represent risk numerically—for instance, saying that a person has a 1 in 100 (or 1%) chance of an outcome. Although qualitative categories may be easier to understand, they are also subjective; one person might view 1% as low risk, while another person might view 10% as low risk. People are more likely to understand categorical recommendations if they are linked to quantifiable, objective data (e.g., “low risk” means that you have between x% and y% chance, as measured by z).
• Link risk categories to specific actions people should take. Communications should be specific as to what, when, how, and for how long people should take action. For instance, it can be useful to provide examples of what is and isn’t considered “low risk” so that people are not forced to make decisions based on their own potentially skewed risk perceptions. Case examples can be useful to show people how to behave under different conditions.
• Carefully consider changing recommendations. The recent guidance that people who are vaccinated against COVID-19 no longer need to wear masks may have had an unintended effect among those who weren’t vaccinated. One week after the announcement, a survey found that unvaccinated Americans were far more likely to say they were comfortable going maskless, compared to vaccinated people. The message some people heard—that no one needs to wear a mask—was not what was intended. Always keep in mind how different people might interpret a change in recommendations. It helps to make the reason for the change part of the core message.

Here are two examples where some of the above principles were put into action with varying levels of success:

A successful strategy

In 1978, the US Forest Service launched the well-known five-color National Fire Danger Rating System (NFDRS) to show the seriousness of burn conditions. The system has been well regarded because it is easy to understand, linked to objective indicators of risk (e.g., relative humidity, flame length, rate of spread), and has clear directives based on current fire danger (e.g., avoid campfires, postpone burning debris, take extra precautions when conducting work that might create sparks).

...that didn’t work elsewhere

Based in part on the success of the NFDRS, the Homeland Security Advisory System was a color-coded threat scale that was used from 2003-2011. Although simple to understand, this system was widely criticized because it was not clear how the threat categories were determined, nor what people should do differently based on current conditions. In fact, the lowest threat levels (green and blue) were never actually used. Yellow (“elevated”) became the new baseline level and people habituated to this level of risk.