Encouraging people to be less likely to express prejudice – and maybe even be less prejudiced – may be as simple as administering a vaccine.

Prejudice may have evolved as a form of self-defense: shunning “outsiders” may have been a way of protecting one's group both from attack and from the risk of new diseases. By the same token, reducing prejudice seems to be strongly dependent upon how immune to disease people are – or, at least, how immune they think they are.

These results suggest how something as simple as feeling safe can help counter prejudice, and may offer an alternative to campaigns to reduce prejudice by characterizing it as undesirable behavior, since these appear to backfire.

Researchers at the University of Toronto demonstrated the immunity-prejudice connection in a series of creative experiments. In the first, the team looked at people who were vaccinated or unvaccinated against the flu, which the researchers suspected might correlate with their attitudes towards “outsiders.” They had half of the vaccinated participants and half of the unvaccinated participants read brochures about the dangers of flu. Finally, the participants answered questions about their feelings towards immigrants.

The people who had read the cautionary materials were less prejudiced if they were also vaccinated. There was no difference in the people who hadn’t read the material. This suggests that when people are more aware of the threat of disease, they may also more prejudiced if they feel that they are vulnerable to it (being unvaccinated).

A second experiment tested how people’s perceptions of safety, beyond their actual safety, influenced their prejudice. The team studied people who were all vaccinated, but some read material underlining the effectiveness of the flu vaccine, while the others just read an explanation of how it works. Then they were questioned about their feelings about other groups of people, like obese people and drug addicts. Those who were reassured about the vaccine’s effectiveness were less likely to demonstrate prejudice than those who weren’t. “Even when everyone is actually protected,” said author Julie Y. Huang in a news release, “the perception that they are well protected attenuates prejudice.”

Finally, a third experiment looked at how the use of something as simple as antibacterial wipes might affect people’s perceptions of other groups. Half of a group of participants wiped their hands and a computer keyboard they were using with antibacterial wipes. They were questioned about their feelings about germs as well as their attitudes towards other groups of people: both “outsiders” (stigmatized groups of people) and “insiders” (their families and fellow students).

Among the people who had not wiped their hands, those who were more nervous about germs were also more likely to show prejudice towards the “outsider” groups as opposed to the “insiders.” The people who had disinfected their hands didn’t show prejudice, even if they were “germ-averse.”

These results suggest how something as simple as feeling safe can help counter prejudice, and may offer an alternative to campaigns to reduce prejudice by characterizing it as undesirable behavior, since these appear to backfire. Our actual safety appears to influence our attitude towards other groups – but our perception of it may be just as important. It’s interesting to think that something as simple as wiping one’s hands could influence one’s behavior towards others. As we understand more about the origins of prejudice, more imaginative and effective ways to counter it can be developed.

The study will be published in an upcoming issue of Psychological Science.