If you’re sharing close quarters with someone during flu season, how would you know they are sick, even in cases where they may not know themselves?

A new global study led by a University of Michigan researcher found that people worldwide—when choosing among their five senses—agree that sight and hearing are the most useful senses, followed by touch, smell and taste.

From the analysis involving more than 19,000 people from 58 countries, some differences were found based on factors such as the country’s level of development and population density—but generally, the researchers found overwhelming agreement.

“Overall, people tended to prefer senses that minimized their own risk of getting sick,” said lead author Josh Ackerman, U-M professor of psychology and an affiliate of the Research Center for Group Dynamics at the Institute for Social Research.

Ackerman is an expert on the psychology of germs. His work delivers insights into how people think about and react to the threat of pathogens, with real-world consequences.

“It’s important to understand lay beliefs about how illnesses present because they can shape people’s actions and behaviors in contexts where disease transmission is possible,” he said.

“These beliefs also have implications for how we judge other people, groups and places that may or may not pose real danger. Believing that others pose disease threats can lead to avoidance, prejudices and support for restrictive workplace and governmental policies.”

Ackerman’s past research has shown that most Americans use and trust their senses for detecting sick people in consistent ways. They rank sight and hearing first and second—above touch, smell and last of all, taste.

Survey response patterns supported what Ackerman has proposed as a “safe senses hypothesis.” That is, people may be biased to prefer using senses that function at a safe distance when assessing whether another person is sick, even if we believe that the more proximal senses, touch, taste or smell, would give us useful information.

“Where we might lean in to smell a carton of milk to detect danger, we’re motivated to avoid proximity with other people when it comes to infectious disease,” he said.

Read the full article on Michigan News.