Disease-avoidant behaviour and its consequences.

Medical conditions that are non-contagious, but that appear contagious, seem to result in the sufferer being avoided. Error management theory (EMT), suggests that such false alarms occur because the cost of infection poses a greater threat to ones fitness than avoidance. Study 1 attempted to demonstrate a disease-related false alarm effect by asking participants, to evaluate a series of vignettes, featuring people with infectious diseases, non-infectious diseases that looked infectious and non-infectious diseases that did not. Judgements of contracting infection under varying levels of contact, and desire to avoid were obtained. Consistent with EMT, a false alarm effect was evident. Study 2 examined the importance of the face as a key indicator of real and apparent infection, by determining whether facial symptoms result in a greater desire to avoid people with infectious and non-infectious diseases. Consistent with expectation, participants reported a greater desire to avoid people with facially displayed symptoms. Together, these results support the idea that humans have evolved a general tendency to avoid individuals with disease signs, especially if displayed upon the face. One consequence is that where a facially displayed disease sign persists, even if known to be benign, its bearer will experience chronic avoidance.