It's that time of year again. Ghosts, goblins and other spooky characters come out from the shadows and into our everyday lives.
For most people, the thrill lasts for a few weeks each October. But for true believers, the paranormal is an everyday fact, not just a holiday joke.
To understand what drives some people to truly believe, two sociologists visited psychic fairs, spent nights in haunted houses, trekked with Bigfoot hunters, sat in on support groups for people who had been abducted by aliens, and conducted two nationwide surveys.
Contrary to common stereotypes, the research revealed no single profile of a person who accepts the paranormal. Believers ranged from free-spirited types with low incomes and little education to high-powered businessmen. Some were drifters; others were brain surgeons.
Why people believed also varied, the researchers report in a new book, called "Paranormal America: Ghost Encounters, UFO Sightings, Bigfoot Hunts, and Other Curiosities in Religion and Culture."
For some, the paranormal served as just another way of explaining the world. For others, extraordinary phenomena offered opportunities to chase mysteries, experience thrills and even achieve celebrity status, if they could actually find proof.
"It's almost like an adult way to get that kidlike need for adventure and exploration," said co-author Christopher Bader, of Baylor University in Waco, Texas. "Other people are sitting at home and renting videos, but you're sitting in a haunted house that is infested with demons."
"These guys who are hunting Bigfoot are out chasing a monster," he added. "I could see the real appeal in going out for weekend and never knowing what you might find."
There is no hard data on how common it is to believe in the paranormal, which Bader and co-author Carson Mencken define as beliefs or experiences that are not fully acceptable by science or religion.
But trends in television programming offer a sense that there is a widespread interest in mystical phenomena that is becoming more common. In the 1970s and 80s, Bader said, there were maybe one or two paranormal-themed shows in the TV line-up. Today, there are dozens, including programs about ghost hunters, psychic kids, haunted homes and even possessed pets.
Plenty of scientists have put energy into debunking paranormal claims. Bader and Mencken wanted to look instead at what drives people to believe.
They started with two nationwide surveys that interviewed a total of more than 3,000 Americans about their beliefs, experiences and interests.
When the scientists broke down the results, they found that people who are moderately religious are most likely to believe in the paranormal. This could be because they are open enough to believe in the unknown, but not so rigid in their religious beliefs to reject mysterious experiences altogether.
The numbers also showed that different types of paranormal entities appeal to different demographics. Women, for instance, are most likely to believe they live in haunted houses. College graduates are most likely to have out-of-body experiences. Unmarried white men are most likely to believe in UFOs.
Bigfoot hunters were perhaps the most surprising group, Bader said. They defied all stereotypes of paranormal pursuers who wear flowing clothes and commune with spirits.
Instead, they were very serious, extremely conventional and often highly professional. In fact, their beliefs contradicted their lifestyles so much that many of them were plagued by anxiety, which drove them even further to stick to their beliefs.
"Their friends and family consider them kooky," Bader said. "Everyone is saying they're nuts. So, they have a real aggressive style and seriousness of purpose. They want to prove everyone wrong."
For one hunter, the search began one day when he was out in the woods and, he swears, he saw Bigfoot cross his path.
"Imagine the stress that would put on your life," Bader said. "You consider yourself a normal, smart guy, and you think you just saw a giant monkey walk in front of you. Now, you have to fit that into your life."
"These are not people trying to explain a crazy world," he added. "They are trying to prove to themselves that they aren't crazy."
Regardless of the person or the phenomenon, paranormal experiences are purely quirks of the human brain, said Michael Shermer, executive director of the Skeptics Society, an educational organization, and founding publisher of Skeptic magazine.
Whether its hearing creaks in an old house or watching dots move randomly on a computer screen, he said, people tend to look for patterns and meanings in everything.
"The default condition in brain is that all patterns are real," Shermer said. "It's just what we do."