How would you feel if I told that your town has seen an increasing number of immigrants from Ethiopia? Do you think your feelings would be different if you had recently had a flu shot? What about if you’d washed your hands just before I asked the question?  

In previous blogs, I’ve discussed research by Mark Schaller and his colleagues examining the Behavioral Immune System—the psychological and behavioral mechanisms that people use to avoid disease. It’s costly to wait till your body actually gets attacked by bacteria and viruses, and sometimes your body loses the battle. Disease has been a historical threat to human survival; as in the case of the decimation of native North Americans by European germs.  

Rather than waiting to catch a disease, then, it is much more efficient to avoid infection in the first place—by staying away from strangers who are sneezing, coughing, or showing other signs of illness. Given that people from far-away exotic locations might also be carrying exotic diseases to which our ancestors did not develop immunity, people concerned about disease might be expected to amp up their avoidance of foreigners. And in fact, Schaller and his colleagues have found this to be the case. Of course, in a multi-cultural society on the newly flattened earth, this behavioral immune response carries the cost of heightened of xenophobia. Canadians concerned about disease, for example, are more opposed to immigration from exotic places (such as Ethiopia or Sri Lanka). 

Rather than simply throwing up one’s hands and declaring “that’s human nature,” evolutionarily oriented social psychologists argue that understanding the mechanisms of prejudice can help us better design interventions. Indeed, a new series of studies by Julie Huang, Alexandra Sedlovskaya, Josh Ackerman, and John Bargh demonstrates some nonobvious preventative implications of understanding the Behavioral Immune System. 

Huang and colleagues conducted their first study at the height of the H1N1 swine-flu epidemic. To prime disease concerns, they had the subjects read news excerpts about the potential dangers of the swine flu. They then had participants fill out a version of the modern racism scale (with items such as: “Over the past few years, immigrants have gotten more economically than they deserved.”) Finally, the researchers asked participants whether they had gotten an H1N1 vaccination. The results indicated that the vaccination immunized subjects against prejudice, with those who had gotten a flu shot showing less racist attitudes than those not given a flu shot. The result was not due to a pre-existing difference in racism between those who get vaccinations and those who do not, because the difference only showed up in those who had been primed with disease concern, not in a control condition.

In a second study, the researchers examined attitudes toward seven social groups generally associated with possible health and culture-related threats (e.g., crack addicts, heroin users, and illegal immigrants). All the participants had gotten a seasonal flu shot, but the researchers altered their cognitive frame on the shot by saying either “the seasonal flu vaccine protects people from the seasonal flu virus” (protection frame) or  “the seasonal flu vaccine involves injecting people with the seasonal flu virus” (contamination frame). Among people chronically concerned about disease, the protection frame boosted positive attitudes toward out-groups (relative to the contamination frame).

A third study again found that people concerned about disease were more negative toward out-groups. However, the researchers were able to erase those negative attitudes with a very simple intervention—asking the subjects to use an antiseptic wipe to clean off the keyboard and their hands as the experiment began.  

As Huang and her colleagues conclude: “Knowledge about the evolved connections between disease and intergroup attitudes can be leveraged to counteract prejudice.” As they note, vaccination and hand-washing are already recognized by public health officials as ways to reduce the spread of disease. Their research suggests that those campaigns can have a double benefit in an open society, by reducing the microbial side-effects of xenophobia. 

Douglas T. Kenrick is author of Sex, Murder, and the Meaning of Life: A psychologist investigates how evolution, cognition, and complexity are revolutionizing our view of human nature.


Huang, J.Y., Sedlovskaya, A., Ackerman, J.M., & Bargh, J.A. (2011). Immunizing against prejudice: Effects of disease protection on attitudes toward out-groups. Psychological Science.Published online Nov. 4, 2011. DOI: 10.1177/0956797611417261.

Related blogs

The Psychological Immune System. Why seeing me sneeze makes you healthier.

The Psychological Immune System 2. When it’s healthy to be antisocial.

Do Unconscious Fears of Infection Influence Your Social Life?

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