Nocebo/Placebo

In The Demon-Haunted World by Carl Sagan, there is a remarkable story about Alvar Nunez Cabeza de Vaca, a 16th-century Spanish explorer who spent 8 years travelling on foot from Florida to Mexico. His account, La relacion, describes extreme hardship, as well as a detailed and sympathetic portrait of the Native American tribes he lived among. Many tribes believed the strange white foreigners to be capable of great healing and begged them to cure their sick. In this way the explorers became reluctant faith healers, and progressed to curing cripples and raising the dead. Soon they could not move for the press of eager villagers and the explorers became very angry. Then,

a strange thing happened… [M]any of them fell ill, and eight men died the next day. All over the land, in the places where this became known, they were so afraid of us that it seemed that the very sight of us made them almost die of fear.
They implored us not to be angry, nor to wish for any more of them to die; and they were altogether convinced that we killed them simply by wishing to.

This is a powerful example of the flip-side of placebo effect, known as the nocebo effect, caused simply by suggestion or belief. It’s a fascinating, highly complex subject and I love Ben Goldacre’s well-reasoned explanation. Well worth the 5 minutes!



NOTE: Ben has re-posted this, along with another very entertaining clip from Nerdstock with delves further into the placebo/nocebo effect. This second clip is hilarious, but NSFW: Nocebo