Have you ever walked into a room and immediately felt that you weren’t alone? There may be no footsteps, no shadow moving across the wall, and certainly no translucent Victorian woman floating beside the window. There is simply a feeling that someone—or something—is there. You turn around expecting to find a person behind you, only to discover an empty room.

If this happened in your kitchen at two o’clock in the afternoon, you might shrug it off. If it happened at midnight while you were standing inside a 200-year-old house where someone had just told you a ghost story, you might interpret that feeling very differently.

This is one of the things I find most fascinating about supposedly haunted places. Before we ever decide whether a strange experience was paranormal, something else has already happened: we experienced something. The chill was real. The shadow looked like a person. The floorboard really did creak. The feeling that someone was standing behind us may have been remarkably vivid.

Science can’t go back in time and tell us exactly what caused every unexplained experience someone has ever had. What it can do is help us understand some of the fascinating things human brains do when we find ourselves in dark, ambiguous, emotionally charged environments. Sometimes those things are wonderfully weird.

Your Brain Has to Make Sense of the Dark

Imagine walking through your house during the day. Your visual system has plenty of information available, so you can easily identify the coat hanging over the chair, the stack of boxes in the hallway, and the tree moving outside the window. Now walk through the same house at midnight, when the coat becomes vaguely person-shaped, the boxes create unfamiliar shadows, and the tree brushes against the window with a sound that could, if you’re already nervous enough, become something scratching to get inside.

Your brain doesn’t stop interpreting the world just because the information available to it becomes incomplete. It still has to make sense of whatever sensory information is available. When a sound or shape is ambiguous, context, expectations, and previous knowledge can influence how we interpret what we encounter.

That doesn’t mean perception is simply invented. There really is something hanging over the chair, and there really is a sound outside the window. The interesting part is how quickly we can move from incomplete sensory information to a meaningful interpretation of what might have caused it.

Most of the time, this ability is incredibly useful. If something moves in the bushes while you’re walking alone at night, waiting until you have perfect visual confirmation before paying attention would not be a particularly useful strategy. Sometimes it makes sense to investigate the possibility that something important is there. The downside is that occasionally the coat gets promoted to intruder—or, during spooky season, to ghost.

The Ghost Story Comes With You

Now let’s make our imaginary house officially haunted. Before you enter, someone tells you that a woman died there a century ago. Visitors sometimes hear footsteps on the stairs, they explain, and several people have reported strange sensations in certain rooms.

You haven’t experienced anything yet, but you now have information you didn’t have before.

Researchers have actually used allegedly haunted locations to investigate experiences like these. In studies at Hampton Court Palace and the South Bridge Vaults in Edinburgh, psychologist Richard Wiseman and his colleagues asked participants to walk through locations associated with reports of hauntings and record unusual experiences.

Participants reported experiences such as unusual sensations, dizziness, changes in temperature, feelings of being watched, and a sense that someone else was present. Reports clustered in particular areas, and the researchers examined environmental characteristics including lighting levels and variations in local magnetic fields. They found associations between some environmental variables and where unusual experiences were reported.

That result deserves careful wording. The study did not establish that magnetic fields, lighting, or any other single environmental factor explains hauntings. It showed that ordinary characteristics of an environment can be associated with where people report unusual experiences. That makes environmental context scientifically interesting without giving us a universal recipe for creating a ghost.

The researchers also examined the role of belief and interpretation. People can encounter similar ambiguous sensations but understand them very differently depending on their expectations and beliefs. One person hears an unexplained creak and thinks, Old building. Another thinks, Someone is upstairs. Someone who already associates the building with ghosts has yet another possible explanation readily available.

When You Can Feel Someone Who Isn’t There

This is where things become considerably stranger.

Researchers use terms such as felt presence or sensed presence to describe the feeling that another being is nearby despite the absence of clear sensory evidence. People may sometimes experience the presence as having a location—perhaps behind or beside them—even though they cannot actually see another person.

Felt presence isn’t limited to ghost stories or people who believe in the paranormal. A 2023 review by Joseph Barnby and colleagues describes these experiences across a remarkable range of circumstances, including neurological cases, psychosis and paranoia, sleep paralysis, anxiety, endurance sports, and spiritualist communities. The authors also make an important point for our purposes: felt presence remains an intuitive but poorly understood experience.

That uncertainty is worth preserving. There probably isn’t one simple mechanism that explains every experience of a presence, and researchers are still investigating connections among bodily awareness, social perception, agency, and the ways we distinguish ourselves from other people.

One particularly fascinating line of research, however, suggests that our perception of our own bodies can sometimes contribute to the experience.

And this is where we get to the ghost robot.

Scientists Built a Ghost Machine

In 2014, neuroscientist Olaf Blanke and an international team of researchers published an experiment with a title that sounds as though it belongs in this series: “Neurological and Robot-Controlled Induction of an Apparition.”

The researchers first studied neurological patients who experienced a feeling of another presence. They then developed a robotic system that allowed them to manipulate the relationship between a participant’s movements and tactile sensations delivered to the participant’s back.

Participants moved one robotic device with their hands while another robot reproduced movements against their backs. The researchers could introduce a delay between the person’s movement and the tactile feedback, creating a conflict among sensory and motor signals that would normally correspond more closely.

Under these altered conditions, some healthy participants reported presence-like experiences. The researchers concluded that manipulating the integration of sensorimotor signals could experimentally induce a feeling of presence and related bodily illusions.

No haunted house was required.

The researchers proposed that problems identifying the source of signals related to one’s own body could contribute to the impression that another presence was nearby. It is a fascinating result because something that feels intensely social—someone else is here—can emerge from altered processing of information associated with one’s own body.

This experiment still doesn’t give us permission to announce that scientists have discovered the neurological explanation for ghosts. The newer scientific literature makes clear that felt presence occurs in many different circumstances and remains incompletely understood. What the Blanke experiment demonstrates more specifically is that researchers can produce presence-like experiences in healthy participants by manipulating sensorimotor information.

That is already strange enough.

Why Haunted Places Are Such Interesting Environments for the Brain

Put some of these pieces together and the classic haunted house becomes an intriguing environment for unusual experiences. It may be dark, reducing the amount of visual information available. It may be unfamiliar, which means ordinary creaks and mechanical noises are new to you. Old buildings genuinely produce unusual sounds as wood, plumbing, heating systems, animals, wind, and people interact with the structure. You may also know the building’s ghost stories, giving ambiguous experiences a ready-made interpretation.

You are probably paying attention differently too. If you’re walking through a supposedly haunted building at midnight, you’re listening for footsteps. You’re watching the corners of rooms. You’re noticing changes in temperature and the sensation of air moving across your skin. Something that would normally disappear into the background can suddenly become important.

None of this means that people who report paranormal experiences are foolish or gullible. Many of the processes involved are ordinary features of human perception. We make sense of incomplete sensory information, use previous knowledge when interpreting ambiguous situations, detect possible agents around us, and direct more attention toward things we believe may be significant.

A haunted house simply gives those processes excellent material to work with.

But Did You Actually See a Ghost?

This is where science has to know its limits.

If someone tells me they once saw their deceased grandmother standing at the end of a hallway, I can’t run an experiment twenty years later and tell them exactly what happened. Maybe there was an unusual perceptual experience. Maybe memory changed over time. Maybe grief played a role. Maybe lighting contributed. Maybe something else happened that neither of us can reconstruct.

Saying that researchers have identified mechanisms capable of producing some ghost-like experiences is not the same as saying science can retrospectively explain every person’s unusual experience. It also isn’t the same as demonstrating a supernatural explanation.

Those are two different standards of evidence, and I think we sometimes forget that when talking about experiences that fall into the category of “woo.” Skepticism doesn’t require replacing one unsupported certainty with another. We can say that there are documented circumstances in which people experience a presence without clear sensory evidence of another person while still admitting that we cannot reconstruct every individual experience after the fact.

Sometimes the most scientifically responsible answer really is that we don’t know.

Maybe the Haunted House Is Doing Exactly What Brains Do Best

There is something wonderfully human about a haunted house. We enter an unfamiliar environment already carrying stories about what has happened there. Our senses gather incomplete information from darkness, echoes, drafts, shadows, and unfamiliar sounds. Our attention becomes heightened because we’re looking for something unusual, and our brains begin the ordinary work of trying to determine what all of those signals mean.

Then a floorboard creaks behind us.

For a moment, that sound may become someone behind us. We turn around and laugh when we discover the hallway is empty, but our heart may keep racing anyway. We may tell the story for the next twenty years because, even after considering all the possible explanations, we still remember exactly how it felt.

That is the part of these experiences I don’t want science to erase. Understanding perception doesn’t make the experience less strange. Knowing that researchers can induce felt-presence experiences by disrupting sensorimotor information doesn’t make the phenomenon boring. If anything, it raises an even stranger question about something we normally take completely for granted: how does your brain distinguish between you and someone else?

Perhaps the most interesting thing lurking in the haunted house isn’t a ghost after all.

It might be the brain we brought inside.

References & Further Reading

Barnby, J. M., Park, S., Baxter, T., Rosen, C., Brugger, P., & Alderson-Day, B. (2023). The felt-presence experience: From cognition to the clinic. The Lancet Psychiatry, 10(5), 352–362. https://doi.org/10.1016/S2215-0366(23)00034-2

Blanke, O., Pozeg, P., Hara, M., Heydrich, L., Serino, A., Yamamoto, A., Higuchi, T., Salomon, R., Seeck, M., Landis, T., Arzy, S., Herbelin, B., Bleuler, H., & Rognini, G. (2014). Neurological and robot-controlled induction of an apparition. Current Biology, 24(22), 2681–2686. https://doi.org/10.1016/j.cub.2014.09.049

Alderson-Day, B., Moseley, P., Mitrenga, K., Moffatt, J., Lee, R., Foxwell, J., Hayes, J., Smailes, D., & Fernyhough, C. (2023). Varieties of felt presence? Three surveys of presence phenomena and their relations to psychopathology. Psychological Medicine, 53(8), 3692–3700. https://doi.org/10.1017/S0033291722000344

Wiseman, R., Watt, C., Stevens, P., Greening, E., & O’Keeffe, C. (2003). An investigation into alleged ‘hauntings’. British Journal of Psychology, 94(2), 195–211. https://doi.org/10.1348/000712603321661886