What makes a place seem 'haunted'?

With its long history of incarceration, brutal conditions, and several grisly murders, the stories of hauntings on Alcatraz Island are a dime a dozen. There are tales of apparitions, cries coming from inside prison walls, and the sounds of phantom cannons and gunshots. Alcatraz sits just over a mile from San Francisco in the waters of San Francisco Bay. Its decaying structures are cold, empty, often shrouded in fog and brimming with tales of mayhem and mystery—all factors that make the island a choice breeding ground for paranormal activity. Or so paranormal investigators would tell you.

The term paranormal refers to experiences and events that are not scientifically explainable, like a UFO or a kitchen chair seemingly moving on its own. These are things that exist beyond the understood laws of nature. But while nothing has ever been proven, some places are more prone to perceived paranormal activity than others. So, what causes a “ghost meter” to spike in one location? What triggers feelings of extreme fear and unease in a so-called “haunted” place? Turns out the answers are more rooted in scientific evidence than you might think.

The importance of setting

Think about the types of places where rumors of hauntings and mythical creatures abound. Many of these places already have stories associated with them. It may be through a tragic history, like Pennsylvania’s Gettysburg Battlefield—site of the bloodiest battle of the American Civil War—or folklore, like Scotland’s Loch Ness. Even certain architectural styles can evoke a sense of gloominess and dread. Take Gothic architecture, which was regularly featured in 18th century literature as a setting for horror and the supernatural and is known for its soaring ceilings, shadowy interiors, and grotesque gargoyles. Chances are when you visit places like these, your senses are already heightened.

“You’re primed to think it’s possible something could happen,” says Marc Eaton, a professor of sociology at Ripon College in Ripon, Wisconsin. “Then when things start happening that lend themselves to an interpretive framework,” like a door suddenly opening, “the conclusion might be made that there’s something paranormal happening.” For example, a ghost has just entered the room.

In the early 2000s, Eaton became interested in the paranormal. As a way to de-stress while obtaining his PhD, he started watching the reality television series Ghost Hunters. The show, which ended in 2016, followed a team of two paranormal investigators into reportedly haunted places, to see what supernatural entities might turn up.

By 2012, Eaton was tagging along with teams of paranormal investigators himself, researching in part their methods for determining whether or not a location is haunted. One thing he learned: Many paranormal investigators place far more emphasis on trying to debunk things that go “bump” in the night than immediately jumping to the conclusion that there’s something sinister at play.

A stone monument topped with a statue of a Civil War soldier standing with his arms crossed. The monument has a dark plaque and is set upon a large rock base surrounded by dry, tall, reddish-brown grass and scrub. Bare trees stand in the background under a cloudy sky. — Gettysburg is often considered one of the most haunted places in the United States. *Image: DepositPhotos*

Paranormal investigations

To picture the sorts of small paranormal investigative teams that Eaten accompanied, imagine the Mystery Gang from the animated series, “Scooby Doo, Where are You?” While the blond-haired Fred Jones is the gang’s primary leader, turtleneck-wearing Velma Dinky is seen as the “brains” in the group, always putting the clues together alongside danger-prone Daphne, food-obsessed Shaggy, and their beloved Great Dane, Scooby Doo. Together the group investigates ghostly, supernatural occurrences, which they almost always debunk.

“I think that paranormal investigators are fairly aware of the fact that most people who are not part of the subculture see them as a bunch of goofballs,” says Eaton. “So they work hard to find multiple sources of evidence.”

Many investigators use a variety of technological tools like pressure and temperature gauges and electromagnetic frequency readers (a.k.a. “ghost meters”) to detect things like atmospheric changes and oscillations in electric and magnetic fields. To paranormal investigators, spikes in these readers signal the potential for ghost activity—meaning it’s plausible that they’re sharing that space with a spirit.

“Say there’s a sudden temperature drop in a corner,” says Eaton. “The next thing that the team members would probably do is to go to that corner and see if there’s a window that’s open, or if there are some loose floor boards that are letting in cold air from the outdoors.”

Basically, they try to find a natural explanation for what’s just occurred, and it’s often relatively easy to.

Natural explanations for paranormal activity

In the 1980s, a British engineer named Vic Tandy was working in a laboratory designing medical equipment when he noticed an ominous grey shape out of the corner of his eye. When he turned to face it, it was gone. Tandy was already aware of rumors that the laboratory may be haunted, though he hadn’t given it much thought previously. The following day, the engineer noticed that a foil blade he’d clamped in a vice for one of his own experiments was vibrating rapidly due to a newly installed fan in the lab. The fan had been creating infrasound, a low-frequency sound wave below human hearing that often leads to dizziness, anxiety, and poor concentration in humans. Tandy turned off the fan and the sound waves disappeared, as did the ominous visions.

This is just one example.

Psychological factors behind the supernatural

When looking at paranormal activity, it’s also important to consider various psychological factors. Some people may have family members who claimed to have extra-sensory abilities, or have grown up in a family where paranormal experiences were a regular occurrence. This most likely will affect how you enter the field, says Eaton, meaning that you may be preconditioned for paranormal beliefs through cultural influences and spiritual experiences. If your mom believes in ghosts, you’re more likely to as well.

Almost everyone experiences pareidolia—the propensity to discern a face or something significant in an inanimate object or random pattern. “People have a tendency to see things that aren’t really there,” says Eaton, “like when you look up at the clouds and see an elephant.”

Pair this with the power of suggestion, a psychological phenomenon in which external cues can influence our thoughts, feelings, or behaviors, often without us being consciously aware of it happening, and suddenly we’re seeing a “hellhound” with glowing eyes roaming a street in New Jersey.

Non-falsifiable information

“I can’t say that I’m now some true believer in the existence of ghosts,” says Eaton, “yet many people that I know have told me they have had supernatural experiences, and they weren’t trying to monetize it.” So the next time you’re touring a place like Alcatraz Island and hear a cry coming from a closed-off stairwell, make of it what you will.

This story is part of Popular Science’s Ask Us Anything series, where we answer your most outlandish, mind-burning questions, from the ordinary to the off-the-wall. Have something you’ve always wanted to know? Ask us.

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What makes a place seem ‘haunted’?