Guest post: Measuring the Immaterial

Measuring the Immaterial: Ghost Hunting Devices, Theory and Skepticism

Guest post by (with a little editorial assistance from Loyd Auerbach)

One could certainly argue that the 21st Century is the “Show Me” era. For any argument to hold water today, tangible evidence must be presented that can be tested and verified through many levels of scrutiny and peer review. This holds in any science in contemporary Western culture, including the study of the paranormal and the serious study of ghosts.

In the words of novelist James Houranin From Shaman to Scientist: Essays on Humanity’s Search for Spirits, “Unlike other cultures, which readily accept belief in ghosts—as either mystical phenomena or culturally useful folklore—Western culture needs to analyze and codify the spirit world.”[1]

These are the fruits of 300 years of scientific labors and unprecedented advancement. Without some form of video or audio evidence—the “Show Me” factor—people will generally think a ghost sighting was a convincing hoax put on by someone in a ghoulish costume sooner than an actual brush with the paranormal.

As a result, in our efforts to codify paranormal activity, ghost hunters have begun to rely on technologies like digital recorders, cameras, temperature measurement devices and the like in increasing numbers. But this begs the question, how “scientific” are our modern devices for measuring actual paranormal activity? And what are the underlying theories justifying their use in such arenas?

The Modern Ghost

Ghosts, in modern times, are often associated with phantom temperature changes, light orbs, vortexes, spikes in electromagnetism, disembodied voices caught on tape (electronic voice phenomenon or EVP) or ghostly apparitions caught on film in either the visible, infrared or full color spectrum.[2] Much of these associations are the result of lingering folklore, hobbyist ghost hunters, and certainly the paranormal TV shows, rather than the evidence gathered by researchers and investigators of the field of Parapsychology (and its predecessor Psychical Research) over the last 130 years.

Underpinning the ‘science’ behind these theories is the unproven assumption that spirits leave behind energy signatures that can be measured in some capacity, with an alternative hypothesis that whatever ghosts are “made of” is something that can affect the local environment, which can be measured. One way to imagine this phenomenon is to picture an invisible boat on a lake. While you can’t directly see the boat, you might be able to see water breaking on its hull or other environmental perturbations caused by the boat. With the proper instrumentation, you may even be able to document the anomalous behavior of the water and conclude, “There’s a boat there.” In the same sense, measuring environmental factors and finding inconsistencies or anomalies is crucial to ghost hunting.

But our boat metaphor leads to one critical question: Why couldn’t the invisible boat be an invisible hippopotamus or an invisible log? While this may sound a bit overly metaphorical, it hits on the ultimate impasse facing ghost hunters once evidence is in hand; where do we draw the line between correlation and causation?

A good place to look for answers is within the devices themselves, and the theories postulated by the paranormal community for the underlying application of each. Unfortunately, many of the “theories” put forth by these folks are either not supported by or contradicted by the evidence (including the actual experiences with ghosts that are reported), field work and research by parapsychologists and psychical researchers.

The Devices in Action

It seems that every year the ghost hunter’s tool belt gets a little more versatile and advanced. In The World of Horror: Ghosts and Goblins, author Sue Hamilton points to a host of devices used in paranormal investigations. Electromagnetic field (EMF) meters, thermometers, thermal imaging scopes, motion detectors, compasses, cameras and digital recorders are all essentials in the ghost hunting utility belt. [3]

Director of the Office of Paranormal Investigations, parapsychologist Loyd Auerbach, M.S., who is also a Professor at Atlantic University, an Adjunct Professor at JFK University and an instructor at the HCH Institute, Parapsychological Studies, provided his expert opinion on each of the major devices listed in the chart below:


Paranormal Use/Theory

EMF Meter

Whatever a ghost is “made of” is something that can interfere with (or otherwise affect) the local electromagnetic environment. If a ghost were made of EM energy, and was radiating it, there would be all sorts of issues with that ghost interfering with all types of electrical appliances and devices (and other materials). However, parapsychology research has shown that psychic abilities are not electromagnetic in nature, and it’s highly unlikely that our presences after death, which use such abilities to perceive the world around them (and move things) would be electromagnetic.


The idea that ghosts can affect room temperatures by drawing from surrounding energies to manifest is an explanation mainly  from the mediums and spiritualists of the past, and posits that spirits can change the temperature in a room by absorbing or giving off energy. Hot spots are sometimes reported, and most often no temperature changes are reported. However, in many reported cases that include “cold spots” or perceived temperature changes, thermometers show no physical temperature change at all. The “cold” is felt, but more of that cold chill we all sometimes get may be psychological or something we’re picking up psychically. Or it may be a misperception of something else physically happening in the environment.

Thermal Imaging Scope

The theory posits that ghosts may even take a shape in the form of a temperature differential, which though invisible to the naked eye, may be visible with a thermal imaging scope. However, these devices typically do not pick up floating temperature differentials (they need a surface), unless certain types of gases (i.e. carbon monoxide, for one of the devices) are floating around in blobs – highly unlikely in a well-ventilated or occupied room.

Motion Detector

The theory is that ghosts can trigger a motion detector the same as any other moving object. Most devices are IR and some are acoustical. There’s been no evidence that ghosts interrupt IR sensors or generate sound to affect them. However, there has been research showing that some people can mentally interrupt IR beams.


Ghosts, able to affect the electromagnetic environment in some way, can also disturb the needle on a compass, though this could also be a result of psychokinesis (PK).


People once believed that ghosts can leave impressions on film, even though the ghost may be invisible to the naked eye. Cameras, however, cannot pick up things invisible to the human eye in general. Most film is not sensitive to such things. Some digital cameras may pick up small traces of the infra-red spectrum (mostly reflections of the IR sensor that is used for auto-focusing) or ultra-violet light (which is extremely unusual), but this does not explain why some people in a room can see the ghost and most people (at the same time) cannot.Today, the theory has evolved and states that in the case of both cameras and recorders, an apparition consciously directly affects the recording media to have an image or voice (either film/tape or digital media) or causes the actual device to create the image/voice (in the case of digital cameras or recorders). However, because we know living people can unconsciously do this as well, it’s also possible the affect is caused by the unconscious PK of an investigator.

Digital Recorders

A common misconception is that ghosts can create vibrations that leave disembodied voices on tape. It  has been clearly shown over the last 40+ years by actual researchers looking at the question of EVP that “vibration” or “sound” has nothing to do with this phenomenon. Recordings have been made with no working microphone in both analog tape and digital recorders. Recordings have “appeared” on devices with backups attached to them not getting anything, and no one hearing anything. Not to mention that the term EVP – electronic voice phenomena – refers to voices created in the device/recording medium itself.
With EVP it’s been noted that certain people seem to always get EVP, while most of their teammates get nothing. Why should that be? Two possibilities: (1) The person is unconsciously affecting the recorders or (2) that person is a kind of medium, unconsciously working with the consciousness that is the ghost to cause the affect.


*Important Note: Psychokinesis (PK) is another major piece of the puzzle to consider. PK is essentially “Mind Over Matter.” The reality is that, while unexplained itself, the idea that a mind affects the devices directly, or physically affects film/tape/recording media, has lots of evidence from both field work and better evidence from laboratory work over the last several decades –though the latter is of course focused on the minds of living people.

PK – by the mind of a living person or a deceased one — is what moves objects, whether a book or chair or compass needle (even, perhaps, the needle on an EMF meter, in which case there really is no EM change – something we have yet to really consider). PK could also effects the workings of a thermal imaging device, or any other device. Unless one has human detectors who can correlate their perceptions with the measurements, all you have are a bunch of anomalous measurements. Without the human experience of ghosts, there’s no context or connection.

Parsing Out the Evidence

Once an investigator believes in a device and that it is measuring the phenomenon they intended to capture, the next thing they need to do is tease apart the situation to the best of their abilities. Essentially, investigators will ask, is there a natural explanation for the phenomenon I’m documenting? Many ghost hunters and paranormal investigators use something like “debunking phase” to describe this. But the word “debunk” has been misapplied by the guys on GHOST HUNTERS and adopted by their fans (and spread rampant through the paranormal community).

The word is related to “bunk” (the earlier word “bunkum”) which is “fraudulent” and used for example to describe the work of con artists. The skeptical movement/community used that word appropriately (for them, given they don’t believe in psychic anything) to “debunk” psychic experiences, phenomena and research coming from the assumption that it was “all bunk” – in other words, fraud (either purposeful or more often self-deluded). It is absolutely the wrong term to describe the required activity for any investigator or research to look for alternative explanations for the reported experiences and phenomena. In other words, science looks for explanations. Science doesn’t go in to situations looking for fraud (though fraud may be found), which is what “debunking” would be. Use of that term is insulting to anyone who has reported phenomena or had experiences with the phenomena, and some parapsychologists have seen clients of ghost hunter groups get upset when the “team debunker” is introduced (as if it’s not the responsibility of everyone in a group to look for alternative explanations).

Several devices, including EMF meters, thermometers, compasses and even cameras need to be treated with careful, unbiased scrutiny because of their environmental and mechanical sensitivities; and it is the responsibility of investigators using them to know what else might affect them.

Consider the case of the EMF meter. “Because EMF meters detect magnetic and electric energy,” writes Amy Rockwood of the Massachusetts Academy of Mathematics and Science, “it is more feasible that the high EMF readings suggest electricity nearby, rather than a ghost.”[4]

Indeed, since many of these devices simply measure environmental factors, one should certainly look for sources of electricity in a building when an EMF spike is detected. Looking for sources of magnetic interference (even kids’ magnets) is also important. Some of the EMF meters – specifically the ones that measure natural fields – often work by detecting the strength of a fluctuation or change in the local field, and even living people can affect such changes. In fact, merely moving such a meter causes a shift, and a measurement.

In the case of thermometers and other temperature reading devices, caution should definitely not be thrown to the wind. Cold spots are often associated with the presence of a spirit. But again, correlation does not necessarily equal causation, and in some cases hot spots have been reported instead of cold. Countless environmental factors can lead to pockets of colder air in a building. Simply put, like water in a lake, the convection of heat in the air is a fluid transfer from hot to cold. Hot and cold spots can come and go as air moves through a drafty home, so this type of evidence should be carefully scrutinized.  In addition, over the last 130 years, parapsychologists/psychical researchers have found that many reported cold spots are actually psychological (like a “cold chill up the spine” one feels watching some horror movies), as no physical temperature change could be found.

Devices like thermal imaging scopes take this type of measurement to the next level. Utilizing infrared technology, a thermal imaging scope allows the investigator to see the size and shape of a cold spot. Should a cold spot suddenly take on humanoid form, while this could still be coincidental, it would certainly seem to be harder to devalue. But the real problem here is that thermal imaging devices need surfaces to “read.” While some will pick up certain pockets of gas floating in the air (as the IR beams reflect back), a typical cold spot or hot spot in mid air cannot be detected by such devices. A passive sensor thermal imaging device would pick up heat being given off, and technically could pick up something in mid-air, however such heat sources would be felt and could be otherwise measured.

However, that does not mean such devices cannot be otherwise affected by a ghost, as parapsychologists/psychical researchers have gathered imaging data that cannot be explained by even the manufacturers. The issue is figuring out how the camera is being affected, as the normal operation of the device is not responsible. Parapsychologists consider psychokinetic effects (mind over matter) as responsible for not only this kind of result but also for EVP and film/digital images of apparent ghosts (and of course, for object movement).

Everything in Moderation


When talking about investigations, there are two types of phenomena where tech can be possibly useful: ghosts (apparitions, or consciousness/spirit of someone deceased) and hauntings (referred to as residual hauntings, or place memory). As hauntings are essentially imprinted in a local environment, this phenomenon is most likely to be repeating, and therefore measurements are more likely to be reproducible.

Keeping that in mind, an open yet skeptical attitude will generally keep you on the straight and narrow when ghost hunting. While there is no way for us to know for certain whether our “invisible boat” is a boat at all, through discipline, repetition and verification across different groups and ghost hunting organizations, the case for these devices will ultimately be built. If modern explanations and science cannot explain observed and documented phenomenon enough times, the link between correlation and causation becomes stronger.

In this regard, by carefully considering all of the environmental factors at hand, looking at evidence critically is perhaps the handiest tool in the ghost hunter’s utility belt. Moreover, a responsible paranormal investigator will always be sure to consider the psychological factors of a case and the possible perceptual mistakes that could be made along the way. These psychological factors may not be responsible for what the devices pick up, but certainly are a part of the witnesses’ experience (which is what the investigators should be investigating). Again, one tries to explain anomalous measurements, not ‘debunk’ them. In fact, if there is any fraudulent activity going on in relation to the devices, it’s going to be on the part of the investigators and not the clients.

At the end of the day, it takes countless hours logged in the lab or field, numerous instances where the same circumstances gave rise to the same or similar outcome, and eventually, exception by the community at large that the prevailing theory is justified beyond a reasonable doubt based on the evidence presented. However, there is one key difference we must remember to consider when studying the paranormal versus certain other (physical) sciences where outcomes are often identical and repeatable.

It is important to remember that there are many natural phenomena which are not necessarily reproducible on demand across many sciences and disciplines, such as astronomical occurrences or even earthquakes – one has to wait until they happen again. On the social science front (and Parapsychology/studying the paranormal is mainly a social science), Psychology, for instance, has an incredibly low replication rate. Similarly, if the ‘phenomenon’ we are studying is ghosts, the only way ghostly phenomena (as opposed to residual hauntings) are going to be reproducible is if the ghosts themselves cooperate. After all, if ghosts are/were people, then they are not “phenomena” per se. They are acting, deciding entities who can choose to produce evidence or inversely, avoid detection if they so choose.

Perhaps even more crucial to remember is that paranormal studies have a constant human element – both through the living and the dead – which must never be overlooked. The question arises: based on what the paranormal community seems to be doing most of the time, it’s not the experiences of humans they’re necessarily interested in. When you take pause, this is rather counterintuitive, since a report by a human of an experience is what is actually being investigated in the first place. The human element is key in this way, as “paranormal” is actually defined by the human experience of it.

Works Cited

Hamilton, S. (2007). The World of Horror: Ghosts & Goblins. ABDO & Daughters.

Houran, J. (2004). From Shaman to Scientist: Essays on humanity’s search for spirits. Scarecrow Press.

Martin, M. (2011). Ghost Hunters. Capstone Press.

Rockwood, Amy Lynn. “On the Hunt for Ghosts.” Massachusetts Academy of Mathematics and Science.


[1] Houran, J. (2004). From Shaman to Scientist: Essays on humanity’s search for spirits. Scarecrow Press.

[2] Martin, M. (2011). Ghost Hunters. Capstone Press.

[3] Rockwood, Amy Lynn. “On the Hunt for Ghosts.” Massachusetts Academy of Mathematics and Science.

[4] Hamilton, S. (2007). The World of Horror: Ghosts & Goblins. ABDO & Daughters.