From haunted houses to creepy clowns terrorizing the US, 'tis the season for spooky — and potentially paranormal — encounters, if only in the name of Halloween fun.
But for some, believing in ghosts is way more real than a simple Halloween prank.
According to a Gallup survey from 2005, about three out of four Americans harbor at least one paranormal belief. And a Pew Research Center survey from 2009 found that 29% of those polled said they were in touch with the dead, with 18% saying they've seen a ghost.
So what is it that makes us susceptible to these beliefs, despite any evidence that they're real.
It has a lot to do with how our brains are wired
Barry Markovsky, a sociologist at the University of South Carolina, told Business Insider in 2015 that the human mind tries to create patterns to make sense of information that's muddled.
"Ghosts are almost always seen under ambiguous circumstances — such as in poor lighting, or when we're just waking up or falling asleep, when our senses are not at their peak function," Markovsky said.
Basically, those who have encountered a ghost are most likely expecting them. That's why they show up in the places we'd expect: haunted houses, or in the places our loved ones used to frequent.
It's related to what we think happens to us after death
Ghosts tend to be the the most common supernatural belief present among different cultures, Benjamin Radford, deputy editor of Skeptical Inquirer magazine and author of "Scientific Paranormal Investigation: How to Solve Unexplained Mysteries," told Business Insider in 2015.
And that might have a lot to do with their relationship to the afterlife, which is also a common tenet of most major religions.