Avoiding disease is essential for survival. Throughout history, deadly infections have forced humans to adapt their ways. One important strategy for protecting ourselves from infection, people avoidance, was recently studied by HKUST’s Professor Jaideep Sengupta and a colleague. Their experiments—carried out before the COVID-19 pandemic—reveal how the threat of infection can alter our behavior in ways that extend to consumer preferences, with implications for product retailing.

Evolutionary psychologists view behavior through the lens of our prehistoric ancestors. The actions of modern people echo the ways that humans secured survival in the deep past. As contagions are spread by close contact, people avoidance could have evolved as a defense mechanism against disease risk, as part of our behavioral immune system (BIS). The study provides a graphic example: “the sight of another individual coughing up phlegm … is likely to instinctively trigger the disease-avoidance motive.”

Disease cues—signs that an infection may be spreading—have rarely been studied in depth. In the consumer context, whether disease cues will actually trigger “people-avoiding” purchases may hinge on several factors. What if a disease is non-contagious, for example? And do disease cues affect all types of product choice equally?

Professor Sengupta’s work examined these and other questions by looking at an important way in which consumers distinguish between products: their“typicality.” Consider the choice of beers in a supermarket. There will be many varieties of lager—a quintessential example of the beer category—but fewer porters, an atypical beer style. As typical products are more popular, they evoke a mental association with many people. Therefore, when disease cues are salient, the BIS might make typical products less desirable to shoppers. “Our rationale is that the threat of contagious diseases evokes fear of infection,” write the authors, “inducing a people avoidance motive, which, in turn, leads to lower preference for typical … products.”

Professor Sengupta’s experiments confirmed that when infection is on people’s minds, they gravitate toward atypical products. After being given reading material about either modes of disease transmission or an unrelated topic, participants were asked to imagine choosing between pairs of products. Those who had just learned about contagion shifted toward the less typical consumer choice—e.g., a niche variety of fruit juice.

This preference for the atypical—subconsciously linked with “fewer people”—is driven by fear of infection and the urge to avoid others. Participants who reported higher levels of fear and a greater tendency toward other-avoidance were more likely to choose the less typical purchase. Also consistent with the BIS, this shift to atypical products was not observed when the the disease was being described as non-contagious: there was then no need to avoid other people.

The effect was also weaker when the products on offer were less associated with physical touch. A dinner plate usually carries strong connotations of touch. However, when participants were asked to imagine choosing a set of plates for wall decoration—removing the mental imagery of eating—the atypicality preference faded. Even just visualizing the use of antibacterial handwipes reduced the effect, showing that people avoidance is dampened when we feel that hygiene is being practiced.

This research shows that the awareness of infection risk has behavioral consequences that go beyond social interactions or explicitly health-related settings. Retailers need to understand the triggers of these effects and how they can be countered through practicable changes.