Whenever the 13th day of the month falls on a Friday, many people in the United States and other western countries like Britain, Germany, and Portugal consider it to be a day of bad luck.
An estimated 20 million Americans are afflicted by a phobia of Friday the 13th according to experts on the superstition, which is formally known as paraskavedekatriaphobia.
Marshall Brain, the founder and editor of the information website, How Stuff Works-dot-com, says people who have this phobia react in different ways, "anything from they will not get out of bed or leave the house, all the way to: they will not travel, leave the house, start a new project or get married."
Many high-rise buildings in the United States don't have a floor numbered 13, and in many cities, there's no 13th street. Marshall Brain says there's some scientific evidence that there's actually a good reason to be concerned about Friday the 13th: in the 1990's, a British Medical journal found that many people decide not to travel by car, train, or airplane on that day.
Moreover, the report found that it is actually statistically more dangerous to travel on Friday the 13th. Even though the traffic's lighter, "more people end up in the hospital on Friday the 13th. So it's almost as though it becomes a self-fulfilling prophecy," Brain says.
What is the root of the superstition that Friday the 13th is an unlucky day?
Gary Weaver, a professor of cross-cultural communication at American University in Washington, D.C., says that in western countries, the day Friday and the number 13 have long been thought to be unlucky. Weaver notes that "…thirteen is often called the 'devil's dozen.' Thirteen people sat at the Last Supper, and Christ was killed on a Friday. The superstition often starts as a religious issue of some sort and is associated with back luck of some sort.
"On the other hand," Weaver says, "in Japan, Korea, and China, the number four is unlucky because the word 'death' in their language is pronounced very similarly to the number four. In China, the government plans to stop using the number four on license plates because it's considered so unlucky."
Then again, says Gary Weaver, the number 13, as well as eight and 14 are thought to be lucky in China because they sound like a good word, like "okay" or "good fortune."
Weaver says the superstition surrounding numbers is related to an occult pseudo-science called numerology, which adherents claim can explain human character, behavior, and even predict the future, exclusively through numerical patterns. Weaver says numerology's appeal to followers is that it appears based on fact, because numbers and the results of various mathematical equations like addition and subtraction are indisputable. For example, there's no denying one plus one equals two. So, says Weaver, if someone observes the same numbers appearing more than occasionally in what could be a coincidence, the person may become convinced that numbers may affect, even order, their lives.
Weaver says that, for example, if he were superstitious, he might be concerned about a license plate issued for his car a while ago by the Department of Motor Vehicles in Washington, D.C. "On my license plate I have four numbers, 6666. Three sixes are often associated with the devil. A lot of people take it very seriously. Many people don't want to get in the car. I remind them, that 'look, it has four sixes. I didn't ask for it. It was an accident.' "
Regarding Friday the 13th, Professor Weaver says students in his class on cross-cultural communication at American University have asked him to postpone an exam scheduled that day. "I've gotten e-mails saying, 'Why are you doing it on Friday the 13th? Why can't you move it?'" "You know," says the university professor, "maybe I will."
He's concerned that if his students believe the day's unlucky, it might affect their performance, and he says he's got to take that into account. The simple fact is that this superstition about a day and a number, while only a superstition, still worries a lot of people, which Gary Weaver says may be the major reason that it lives on