Ghostbusters: Hunting Ghosts to Teach Scientific Skepticism

Posted October 12, 2017

By Rodney Schmaltz

Nearly all students have a ghost story, be it a personal one, or a tale from a friend. The belief in ghosts is prevalent. A 2016 survey showed that nearly 47% of Americans believe that places can be haunted by spirits (link to, with similar numbers found in Canada and even higher in the UK. Ghost hunting shows are popular on television and there are countless films focused on ghosts and spirit possessions, with some claiming to be based on a true story. This interest in ghosts can provide the basis for an engaging class exercise that can be used to drive home key psychological concepts (Rockwell, 2012). It’s time to turn your students into ghost hunters.

A ghost hunt allows students to carefully consider methodological issues, as well as a broad range of topics such as scientific thinking, cognitive biases, and expectancy effects [1]. To begin this exercise, I have students watch an episode of a popular ghost hunting television program. There are countless episodes available on YouTube. I prefer the UK version of Most Haunted, as there is a psychologist, Ciaran O’Keeffe, who is often on the show and acts as a skeptical voice amidst the other overly enthusiastic ghost hunters and psychics on the program. Remarkably, nearly every episode of any ghost hunting program ends with the discovery of a ghost. The purpose for watching the ghost hunting program is to examine what methods and tools are used, and consider the validity of these methods from a scientific perspective. Students can discuss what makes a good theory, how to develop hypotheses (ie., the need for a hypothesis to be falsifiable), independent and dependent variables, and issues of confounding variables and bias among others.

Most Haunted host Yvette Fielding during filming of an episode [Image: Ian French,, CC BY-SA 3.0,]

The ghost hunting activity has two grade components. The first is to be completed after the location of the hunt has been established. Students are asked to conduct archival research and learn everything they can about the location, with a focus on any reported paranormal activity. It has been my experience that some students have difficulty understanding the value of different types of methodologies. This assignment highlights how multiple approaches to data collection are often used to answer a single question. In this case, students are conducting archival research which will be used to inform experimental work – namely an experiment to test for the presence of ghosts.

The second graded component is a research paper based on the findings from the ghost hunt. The goal of this paper is to get students thinking about research methodology, and more broadly, how to evaluate extraordinary claims. I instruct the students to write the paper as though they were going to submit it to a peer reviewed journal. This allows for discussion of the peer review process, and how to identify reputable sources.

Not all students feel comfortable with the idea of searching for ghosts. As such, I make attendance at the ghost hunt optional. For students who choose not to go on the ghost hunt, they are to complete a similar assignment. Instead of attending a haunted location, the students are assigned to critique an episode of a popular ghost hunting television program and describe if the evidence presented in the program is sufficient to determine the presence of ghosts. The ghost hunt is typically conducted in the evening outside of class time. By having the ghost hunt outside of the regularly scheduled class, students are free not to attend if they don’t feel comfortable, and can attribute this to a problem with their schedules, work, etc.

While the tone of this exercise is generally positive and fun, instructors need to be careful not to alienate any students who believe in ghosts, or who claim that they have seen a ghost. A good way to do this is to have a discussion of the difference between scientific skepticism and cynicism (Sagan, 1995). Psychologists promote scientific skepticism, meaning that we do not dismiss ideas out of hand, but we do require extraordinary evidence for extraordinary claims. This can lead to an interesting discussion on what evidence the students would need before they could be entirely confident that a location is haunted. As students present ideas, instructors will be able to talk about issues such as the need for rigorous scientific methods when attempting to make causal claims, the problems with relying on anecdotal evidence, and how cognitive biases, such as confirmation bias, can lead intelligent people to believe outlandish things. One way to frame this activity is that as scientific skeptics, we can allow for the possibility that ghosts exist, though we would need extraordinary evidence. The goal of the ghost hunt is to attempt to find this evidence.

One of the most difficult aspects of this assignment is finding a location for the ghost hunt. A good place to start is to do research on some of the “haunted” locations in your area. It is valuable to ask students for suggestions, as they may know of a building or location that would be appropriate. When you are deciding on the location to conduct the ghost hunt, you will need to consider whether the location is large enough to hold your class, whether the area is easily accessible, how students will arrive at the area, and of course, the safety of the location. All of the ghost hunts I have conducted have been at local businesses. For example, one of the houses we explored was a marketing firm whose main office was in a building that was over 100 years old. Supposedly there was a ghost of an old man with a top hat on the upper level, and the ghost of a small girl in the basement. While most employees did not believe that the building was haunted, they did report some unusual activity, and even invited a local medium to try to make contact with the ghosts. This highlights a need to be sensitive and respectful when requesting access to the “haunted” location, as some of the people who work in the building may truly believe that it is haunted. I am always upfront that this activity is one grounded in skepticism.

It is best to avoid places like graveyards. While this may seem like an obvious choice as the space is open to the public, there are potential problems. As mentioned earlier, the tone of the ghost hunt is generally fun, with lots of laughter (often nervous). This could be seen as disrespectful to someone who is grieving in this area. As well, while a graveyard is public space, it is not intended for large groups and you may be asked to leave. By having permission at a privately owned location, you will be confident about the amount of time you will be able to spend with the class, and you will not have to be concerned about offending members of the public.

The ghost hunt should be conducted in the early evening, after it is dark. Nearly all ghost hunting programs show footage from a ghost hunt at night, and some ghost hunters claim that the spirits only come out after dark. Shadows created by the moonlight can also lead to the experience of pareidolia – the perception of a pattern or form that does not actually exist (Sagan, 1995). For example, during one our ghost hunts a student noticed a floating figure that appeared to be a person suspended in midair. Upon closer inspection, it was simply the way the reflection of the moon fell upon a group of trees. In the marketing firm mentioned earlier, there were reports of a ghost with a top hat. We found that if you stood across the street, you could indeed see a figure that somewhat resembled the description of the ghost. It didn’t take long to realize that this effect was created by the reflection from the headlights of passing cars.

Conducting a ghost hunt at night also increases the likelihood of finding orbs. Popular ghost hunting programs often mention orbs, which are glowing dots or circles found in photographs that supposedly indicate the presence of a ghost. In fact, orbs are usually the reflection of the camera flash on moisture or dust particles in the air (Nickell, 2006). The photo below was taken during one of our ghost hunts and is packed with orbs. The night of this particular ghost hunt it was raining lightly, the reflection of the flash against the rain led to the presence of orbs in the photo.

[Image: Rodney Schmaltz, used with permission]

The materials needed to conduct a ghost hunt are relatively inexpensive. According to some ghost hunters, spirits may disrupt or create electromagnetic frequencies (e.g., Fielding & O’Keefe, 2008). An EMF meter to measure electromagnetic fields can be found for less than twenty dollars online. EMF meters detect electrically charged objects, such as wall outlets, cell phones, computers, and lamps. The EMF meter is a fun component of the ghost hunt, as it will invariably go off, providing students with the opportunity to determine the source of the electromagnetic activity. This exercise leads nicely into a discussion of confirmation bias. Confirmation bias is the tendency to seek out or search for information that confirms or supports our beliefs, and to reject or distort evidence that goes against our preexisting beliefs (Nickerson, 1998). Someone who believes that a location is haunted is likely to accept that any reading on an EMF meter is a sign of the spirits. A skeptic, on the other hand, may search for more earthly explanations.

Students should also be equipped with a pen and paper, flashlights, cameras and video cameras (which they will have if they bring their phones), a digital audio recorder, and thermometers. While some ghost hunting television programs will have more sophisticated equipment, this will be enough to get started and also lead to a discussion of whether the additional equipment found on ghost hunting shows provide any additional evidence or support for the existence of the supernatural. On many of the ghost hunting programs, a medium or psychic is involved to help contact the spirits. In lieu of a medium, I bring a Ouija board and have students attempt to contact spirits. This exercise allows for discussion of the ideomotor response and the power of expectation in driving many of the findings of paranormal events (see Hyman, 2007).

An original Ouija board. [Image: Public Domain]

Students are broken down into groups of 4 or 5, and given time to explore the location. Ideally, the location should be large enough so that there are several areas for groups to explore independently. Older homes are ideal, as one group can be outside, another upstairs, one downstairs, and so on. Unless the ghost hunt is conducted in a very large area, fifteen minutes to explore each location is sufficient.

Some of the things the students will be looking for are cold spots. According to ghost hunters, small cold areas in a haunted location may be a sign of a ghost. The students can use the thermometers to check if there are any differences in temperature. If there are variations in temperature, students should look for reasons as to why a particular area may be colder (e.g., near a window, in a basement, etc.).

Students should be instructed to take careful notes and detail if there are any unusual smells, sounds, or if there were certain rooms or areas that might make them feel uneasy or frightened. Unexplained odours are supposedly another sign of a potential ghost. If students do find areas that have strong odours, the challenge again is to try to find the source. In one of my class hunts, the owners of the location of the ghost hunt said that some of the rooms had an occasional smell of perfume, which they attributed to the spirits living in that room. Upon investigation, this room was directly above a small store which sold strong smelling soaps. Another mystery solved! This discovery lead to a fruitful discussion on Occam’s razor. I posited to the students to consider which explanation was more parsimonious – that a spirit has returned from beyond the grave and was wearing strong perfume, or that the smell of soap wafted from the main floor of the building to the second floor.

In some ghost hunts, you may find that all students agree that one particular area made them feel uneasy or made the hair on the back of their neck stand up. It is often the case that infrasound is to blame. Infrasound is a low frequency sound under 20 HZ that is outside the limit of human hearing (Leventhall, 2007). Although humans cannot hear infrasound, there is some research indicating that infrasound can cause a mild physiological response, such as feelings of awe or suspense (e.g., Tandy & Lawrence, 1998). Infrasound can be created by heavy traffic, thunder, or low rumbling pipes. Many older buildings have pipes that create infrasound. Infrasound detectors are very expensive, but there is a workaround. Instructors should bring a set of matches or a lighter on the ghost hunt. If there is no breeze, light the match in the location of the suspected infrasound. If the flame starts to turn in a circle, or appears to bend, it is likely that infrasound is present. This method won’t provide you with the precise amount of infrasound, but at the very least you will be able to demonstrate to students that infrasound is the explanation for the ghostly sensations.

Following the ghost hunt, I use the next scheduled class to review what students experienced. Most are surprised at how things that initially seemed to indicate the presence of a spirit turned out to have mundane explanations upon further investigation. For example, during one ghost hunt, students reported that they could see the shadow of a headless body near a bridge. This was particularly frightening, as the students knew that this was also the location where a person hung themselves. Upon further exploration though, students realized that this was created by the way the moonlight was lighting a tree stump. Examples such as this allow students to discuss key issues related to scientific thinking, such as ruling out rival hypothesis, Occam’s razor, and how extraordinary claims require extraordinary evidence.

The ghost hunt assignment drives home key concepts, and is an engaging and memorable experience for students. For anyone who is interested in this assignment, I would be happy to provide a copy of past assignments via email ([email protected]). Happy hunting! 

[1] For a full overview of the range of topics that can be covered in a ghost hunt, as well as some interesting examples and techniques to approach this exercise, Joe Nickell’s (2012) book, The Science of Ghosts, is an ideal resource.  


Rodney Schmaltz is an Associate Professor of Psychology at MacEwan University. His research focuses on pseudoscientific thinking, with an emphasis on strategies to promote and teach scientific skepticism. 


Hyman, R. (2007). Ouija, dowsing, and other seductions of ideomotor action. Tall tales about the mind & brain: Separating fact from fiction, 411-424.

Leventhall G. H. (2007). What is Infrasound? Progress in Biophysics & Molecular Biology, 93, 130-137.

Nickell, J. (2006). Ghost hunters. Skeptical Inquirer, 30(5), 23.

Nickerson, R.S. (1998). Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology, 2, 175 – 220.

Rockwell, S. C. (2012). Ghost Hunting as a Means to Illustrate Scientific Methodology and Enhance Critical Thinking. Communication Teacher, 26(3), 158–162.

Sagan, Carl (1995). The Demon-Haunted World – Science as a Candle in the Dark. New York, NY: Random House.

Tandy V., Lawrence T. (1998). The ghost in the machine. Journal of the Society for Psychical Research, 62(851), 360–364.