The case of the meowing nuns is one of the more bizarre cases of mass hysteria recorded in history. In the 14th century, a nun in northern France began meowing like a cat. Within a week, the rest of the nuns had picked up the practice, and they would spend hours together meowing and purring, sometimes for hours. In the sixteenth century, hundreds of people in Strasburg, also in France, were subject to a dancing frenzy so prolonged that some died of heart attacks and strokes. In both cases, the official explanation was possession by the devil, and the sufferers were forced to pray until they were cured.

In the 17th century, over 19 counties in England organised militias to defenced against ‘Wild marauding Irishmen’, who they believed to be on their way, despite a complete lack of evidence (and Irishmen). That’s a pretty impressive misinformation campaign, and completely without the benefit of the Internet.

The persecution of witches in one place after another over a period of around 500 years is another example of how easily people believe something that isn’t true and not only twist the facts to fit but also see, hear, and otherwise sense things that didn’t happen. Likewise the rash of ghost and monster sightings of the nineteenth century. In the twentieth century, police in a number of countries spent weeks, even months, investigating non-existent crimes because of a whole group of witnesses sincerely believed they had seen them happen, or even been victims.

The Satanist ritual abuse scare of the 1980s and 90s was another widespread phenomenon that has been thoroughly exploded in investigation.

We are creatures of our environment, affected by the beliefs and practices of those near to us. If there is a lesson to learned from this, it is be careful who you listen to.