If you’re in close proximity to someone during influenza season, how can you discern if they are unwell, particularly in scenarios where they may not be aware themselves?

A recent international study conducted by a researcher from the University of Michigan discovered that individuals globally—when selecting from their five senses—agree that vision and hearing rank as the most effective senses, followed by touch, olfaction, and gustation.

From the investigation involving over 19,000 participants from 58 nations, certain distinctions were observed based on factors such as the nation’s level of advancement and population concentration—but generally, the researchers found overwhelming consensus.

“Overall, individuals tended to favor senses that reduced their personal risk of falling ill,” stated lead author Josh Ackerman, U-M professor of psychology and an associate of the Research Center for Group Dynamics at the Institute for Social Research.

Ackerman specializes in the psychology of pathogens. His research provides insights into how individuals perceive and respond to the threat of germs, with tangible effects.

“It is crucial to comprehend popular beliefs regarding how illnesses manifest because they can influence people’s actions and behaviors in situations where disease transmission is feasible,” he mentioned.

“These beliefs also affect how we evaluate others, groups, and places that could potentially pose genuine threats. Assuming that others present disease risks can lead to avoidance, biases, and support for restrictive policies in workplaces and governments.”

Ackerman’s earlier studies have indicated that most Americans utilize and trust their senses for identifying sick individuals in consistent manners. They prioritize sight and hearing—above touch, scent, and finally, taste.

Survey response trends reinforced what Ackerman has proposed as a “safe senses hypothesis.” This suggests that individuals may be inclined to favor senses that operate at a secure distance when determining if another person is ill, even if we believe that closer senses such as touch, taste, or smell could provide beneficial information.

“While we might lean in to sniff a carton of milk to detect danger, there’s a motivation to avoid closeness with others concerning infectious diseases,” he explained.

Universal perceptions

But are these sensitivities global?

The new study, published in Brain, Behavior, and Immunity, investigates whether these tendencies are consistent worldwide.

“One possibility is that we could observe cultural differences influencing the senses we use and believe will be effective in identifying illness in others,” Ackerman noted. “Culture can shape social norms, perceptions about contaminants, and even which senses we might prioritize. Conversely, we might share similar beliefs with individuals across cultures.”

The results revealed that perceptions regarding sensory detection of infectious diseases are remarkably consistent among cultures.

Understanding variance and consistency

In the few instances where variation appeared, it was primarily between the rankings of hearing and touch. Participants from nations with lower latitudes, less wealth, and a heavier disease burden made fewer distinctions between these two senses.

Some might speculate about elements like education, cultural practices, or exposure to disease that could explain these exceptions, Ackerman pointed out, but the variation identified in the study was minimal compared to the widespread consistency of perceptions observed.

“It could be that the world holds uniform ideas about sensing disease because dangers manifest similarly across human communities and because the beliefs individuals possess have effectively supported survival over time,” he said. “However, this doesn’t necessarily imply that we can reliably trust our senses to detect hazards accurately.

Ackerman’s previous research found that individuals are ineffective at identifying sick people based on the sounds of their sneezes and coughs. Instead, it may be that the bias to believe that all “disgusting” noises imply danger is useful and adaptive, as the cost of overlooking infection risks may outweigh the price of false alarms. Reliance on our socially distanced “safe senses” might also be a common inclination that benefits us by curbing the spread of infections, he added.