About 17 million people with friggatriskaidekaphobia (fear of Friday the 13th) probably cringed when they looked at their calendar this morning.

But even if Friday the 13th doesn’t faze you, polls reveal that most Americans admit to being at least a little superstitious.

Do you ever wonder where some of these superstitions come from, or why superstitions can hold such power over us? Like these superstitions, for example:

• Saying “Bless You” when someone sneezes. In ancient times it was thought that a sneeze was a sign of illness. Hence covering your mouth when you sneeze would prevent your soul from escaping. Others would say “bless you” for added protection.
• Full moons lead to chaos and psychosis. Lawyers in 19th-century England employed the "guilty by reason of the full moon" defense to argue their "lunatic" clients could not be held accountable for the influence the moon had on their actions.
• Making a wish on a wishbone. Legend has it that first-century Romans used to fight over dried wishbones as they believed wishbones brought the bearer good luck. Inevitably the tug-of-war over the bones led to breaks and the idea that whoever has the largest bit of bone gets their wish.
• Wearing amber to protect your health. In medieval times when medical knowledge was limited, amber was thought to warm the heart and protect you from colds and flu. To this day, many believe that certain gemstones hold healing powers.

Helpful or Harmful?

Experts say holding a superstition is usually harmless and may actually boost your confidence and performance. There is a positive placebo effect-- if you think something will help you, it may do just that. Any athlete or sports fan can attest to the power of superstitions.

Stuart Vyse, PhD, and the author of Believing in Magic: The Psychology of Superstition, says there can be a real psychological effect of superstitious thoughts. If you've done well before when you wear a particular shirt, for example, it might be a good idea to wear the shirt again, if it helps to relieve anxiety and promotes positive thoughts. However this way of thinking can backfire if you lose your lucky object.

Superstitions can also have a negative impact when they are phobic (fearful) superstitions that interfere with your life and cause a lot of anxiety. Today, Friday the 13th, for example—some people might change travel arrangements or skip an appointment because of unnecessary fears. These types of superstitions can be counter-productive and harmful.

Sources:

MSN Health

Medicine Net

MSNBC