It turns out that a significant amount of people report having personally experienced paranormal activity. In a study published in 2011, 28.5 percent of undergraduate students surveyed at a southern university reported having had a paranormal experience. In a 2006 Reader’s Digest poll, 20 percent of respondents (21 percent of women and 16 percent of men) reported that they had seen a ghost at some time in their lives.

But it’s also true that if you already believe in ghosts, or are told a place is haunted, you are more likely to interpret events as paranormal. A 2002 study found that believers in ghosts were more likely than non-believers to report unusual phenomena while touring a site in Britain with a reputation for being haunted. Visitors who were told that there was a recent increase in unusual phenomena occurring at the site also reported a higher number of unusual experiences on the tour.

Another study demonstrated that hearing or reading about paranormal narratives, especially when the story came from a credible source, was enough to increase paranormal beliefs among participants.