During my almost twenty-five-year career as an engineer, I have come to embrace one guiding principle when it comes to data gathering: never trust the output of any instrument without understanding its inner workings—what it measures, how it works, its parameters, tolerances, or calibration. Just as investigators must understand the mechanics and reliability of their equipment before trusting its readings, the same scrutiny should apply to any method used to gather information—including mediums, whose claims remain unverified by conventional standards.

Mediums often present their information as factual confirmation of otherworldly communication. However, unlike with scientific instruments—whose performance can be verified with stated error margins and calibration data readily available—the output of a medium’s readings remains confined to subjective reports.

Allowing a medium’s testimony to shape the direction of an investigation introduces a significant risk of steering investigative efforts down misleading paths of enquiry. The narrative crafted by the medium could end up dictating the direction of the investigation, pulling focus away from objective evidence. Once unverifiable claims are allowed to lead an investigation, it becomes increasingly difficult to untangle genuine anomalies from the influence of subjective interpretation.

Ghost-hunting entertainment television shows like Help! My House is Haunted, and before it, Most Haunted, normalised the use of mediums on paranormal investigations. Even when Derek Acorah was ousted from Most Haunted after being exposed as a fake by the show’s own resident parapsychologist Ciarán O’Keeffe, the show’s producers chose to backfill the roster with another medium rather than reassessing the role of mediumship in investigations. This decision reflected a clear preference for preserving the show’s established entertainment format rather than prioritising investigative integrity. By maintaining the illusion of supernatural communication as a core feature, they reinforced the expectation that any paranormal investigation must include a medium, regardless of credibility. Many amateur groups seeking to emulate these shows often follow suit, employing self-proclaimed mediums in prominent positions within the team, up to and including lead investigator roles.

A Matter of Ethics

In the case of Help! My House is Haunted, the format typically revolves around the team entering the homes of members of the public, relying on the team’s resident medium to determine the nature and cause of any paranormal activity. Often in shows like this, the paranormal activity is presented as negative or dangerous, on the strength of the medium’s testimony. While the show exists for entertainment purposes, many amateur teams seeking to emulate it might offer similar services.

Such practices are unethical and potentially dangerous, especially when dealing with members of the public who might be vulnerable and genuinely fearful of the activity they believe they are experiencing. The risk of causing serious psychological harm or distress is extremely high on “home callouts,” and while organisations like ASSAP and the SPR do perform such investigations on occasion, it is only done after serious consideration of the risks and the unique aspects of the case. In the case of ASSAP, only those with specialised training and appropriate DBS checks are allowed to participate in such investigations. Even then, the aim of the investigation should be to reassure the client and attempt to debunk the activity, not exacerbate the fear they might be feeling.

Extraordinary Claims…

Mediumship itself is an extraordinary paranormal claim—one that demands rigorous testing and validation before being accepted as fact. As Carl Sagan famously stated, “extraordinary claims require extraordinary evidence” — an extraordinary claim alone does not constitute proof. Using a medium’s statements as evidence of paranormal activity only compounds uncertainty, substituting speculation for verification. Stacking unverified claims does not strengthen an argument—it actively weakens credibility, making genuine investigation harder rather than more convincing. If one were to argue that a medium’s claims prove a haunting, it would be akin to asserting that the Loch Ness monster exists simply because an alien abductee claims their captors told them so—layering one unverified assertion upon another does nothing to establish truth.

Historical Validation?

It is often argued that when a medium’s testimony aligns with historical records uncovered later in an investigation, this provides evidence of a genuine ability. However, there are simpler explanations that must be considered—such as prior research or environmental cues that the medium may have noticed, whether consciously or not. Without strict controls, it’s impossible to determine whether the information was truly accessed through psychic means or simply gathered beforehand.

If a medium were ever to be used in an investigative capacity, extreme care would be needed to ensure they had no prior opportunity to research the location. Additionally, the site itself would need to be vetted to remove inadvertent clues that could unintentionally inform their statements. However, implementing such precautions shifts the investigation’s focus away from the location itself, turning it into a test of the medium rather than a search for genuine phenomena.

Tricks of the Trade: The Techniques Behind Fake Psychic Readings

I have witnessed first-hand performances by the likes of Derren Brown (both on stage and on a one-to-one basis), who employs techniques known to be used by many fake mediums to deliver extremely impressive “readings”—discerning details from audience members’ lives that he would have no way of knowing. The difference in the case of Derren Brown is that he is extremely open about the fact that he has no supernatural ability, and he is using psychological techniques such as cold reading and the Barnum effect to create the illusion of insight.

Cold reading is a set of tactics that allows the practitioner to extract information from a person without them realising it. This can include making broad statements that seem personal but apply to most people, closely observing subtle cues (such as facial expressions or nervous habits), and leading questions that encourage the subject to unknowingly reveal details. Many fake mediums use cold reading to make it seem as if they’re “connecting” with spirits, when in reality they are piecing together information the sitter provides unknowingly.

The Barnum effect, named after the showman P.T. Barnum, plays into people’s natural tendency to see vague, general statements as personally meaningful. For example, a medium might say, “You sometimes feel like you don’t fit in, but you also crave connection”—a statement so universally applicable that almost anyone could relate to it. When paired with a suggestive atmosphere, believers interpret these statements as direct evidence of a psychic connection.

Mediums often combine these techniques with hot reading, where they secretly gather information beforehand—perhaps researching the person online or overhearing conversations before a reading. By blending cold and hot reading with the Barnum effect, a fraudulent medium can leave a believer convinced they’ve just received a genuine supernatural message.

With knowledge of these practices, I have yet to meet a medium that has impressed me as anything other than a skilled practitioner of these deceptive techniques—in fact, many of them are considerably less convincing than someone like Derren Brown or other similar “mentalist” acts, who openly admit to using psychological principles rather than paranormal ability.

Conclusion

In an investigation seeking credible evidence of the paranormal, mediumship must be used with extreme caution—if at all. The risks of disruption, misdirection, and unverifiable claims often outweigh any potential benefit, meaning in many cases, it may be wiser not to use them at all. This is not to say that mediums should be barred from attending investigations altogether—they absolutely can attend as individuals. However, their alleged abilities should never be relied upon as genuine evidence, and any claims they make must be critically scrutinised rather than accepted at face value.