A study at Queen Mary University of London gave people the task of either predicting or maintaining the health of a baby (fortunately not a real baby). People who were given constant advice and updates, even if those updates were praise, tended to do worse than people who were left alone. The idea is that, in order to do a good job at anything, people need to focus and make the right decision. Listening to other people’s opinions made them lose focus and screw up. The more complex the task, the more warm and loving encouragement seems to ruin people.
The key to a psychologically devastating curse is helplessness. Helplessness cultivates a condition called diastolic flaccidity, which is an extreme drop in blood pressure. It’s been linked to the deaths of seemingly healthy people who believe they are cursed.
Among people from China and Japan, including those who emigrated to new countries, the rate of heart attacks goes up on the fourth of every month. The number four is considered unlucky in China and Japan. In many Eastern countries, people skip the fourth floor of buildings instead of the thirteenth the way people do in the West. Given the number of heart attacks, they’d probably be happy to skip the fourth of the month, too, but it’s not practical. So the fourth comes up every month, no matter what anyone does. That sets up the combination necessary to kill someone: fear, awareness, and helplessness.
Sursa: Curse Me Like You Mean It: Using Psychology to Make Your Curses Actually Work