The BPS highlights a study:

When it comes to avoiding infection, a growing body of evidence suggests we don't just have a physiological immune system, we also have a behavioural immune system - one that alerts us to people likely to be carrying disease, and that puts us off interacting with them. Indeed, there's research showing that people who are more fearful of disease tend to hold more xenophobic attitudes and to display greater prejudice towards people with outwardly visible disabilities. Now Chad Mortensen and his co-workers have extended this line of research by showing that a disease-themed slide show makes people feel less sociable and extravert, and primes their motor system for repelling other people.

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