In June of 1962, 60 workers in a U.S. textile mill began to come down with bizarre symptoms: rashes, nausea and numbness. The media quickly latched onto the story, naming it the “June Bug Plague” for the insects the workers believed were making them sick. Yet entomologists called to the scene found no trace of June bugs.

Psychologists who interviewed the sick workers found that more than 90 percent of victims worked the same shift, most worked overtime hours and that 50 of them only began reporting their symptoms after they had seen media coverage of the outbreak. Stress, coupled with the power of suggestion, were the likely culprits.