Apart from gruesome scenes from a string of horror films, Friday the 13th conjures up images of strange happenings and evil spirits. Joanne Earp spoke to a leading psychologist to find out the reason why.

You might not own a rabbit's foot, have a lucky number or carry out a daily ritual, but we all live a part of our lives according to superstition.

It isn't necessarily a conscious effort, a lot of early superstitions which had magical qualities are now just seen as the 'polite' thing to do.

In traditional folklore for example, shaking someone by the hand came from a desire to make better friends and using the right hand was meant to be lucky.

A lot of ancient superstitions tend to return to popular thinking in extraordinary circumstances such as war or an epidemic. However, one superstition which has stood the test of time and continued to capture the imagination is Friday the 13th.

Stephen Sayers is a psychologist at Leeds Metropolitan University specialising in ancient folklore, calendar customs, myths, legends and New Age phenomena.

He said: "Some people have always believed that Friday is an unlucky day and that 13 is an unlucky number, so to put them together is double trouble.

"A lot of superstitions relate to Christian beliefs. Friday was the day of the crucifixion and apparently the day that Eve offered the apple to Adam. It was also a day when people were hanged.

"Coupled with that, there were 13 people at the Last Supper when Christ was betrayed and there are 13 witches in a coven. So, one person's religion can be another person's superstition."

Whatever the reasons, some still believe that Friday the 13th is bad news, and some people even refuse to leave their houses for fear that something terrible will happen to them.

Mr Sayers said: "It is a bit like a self-fulfilling prophecy. You might go six or seven years without anything bad happening to you on Friday 13th and it doesn't bother us - but the one time something does happen it is a chance for us to become irrational.

"Also it is very difficult to separate superstitions from urban myths. There was a story doing the rounds in West Yorkshire a few years ago which came about after a spate of house fires.

"Every house the fire-fighters went to had a picture of a crying boy on the wall, so it became bad luck to have the painting in your living room. Apparently someone took a crying boy picture into one of the fire stations and all the fire-fighters left the building."

Some of the most superstitious people are soldiers, who carry just about every lucky charm going in the hope that it will keep them from danger. And bikers will always put their helmet down neck first, because putting it down head first means that the wearer will be involved in a crash. Other superstitions apply only to the individual concerned. Mr Sayers said: "I knew of a man who worked in a laboratory which had a black and white checked floor. He couldn't bring himself to step on the white tiles."

It is also possible to catch a superstition. "A man I know once read that Romans always put their right boot on first before going to battle - ever since then he has made a point of putting his right shoe on first for good luck," he said.

But, if it works then why not? I knew a Newcastle United supporter who used to keep the front door open during matches because it signified attack, and the back door locked because it signified defence. When the teams changed ends at half time, the front door was bolted and the back door unlocked.

Mr Sayers said: "It's just another way of doing things. People are just looking for new forms of magic. I am mildly superstitious myself in that I don't like talking about projects before they happen - counting my chickens before they hatch.

"If everyone stops talking about the stigma attached to Friday 13th, generations from now it might be just another day."

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.