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The experience of sensing an unknown presence can be frightening.
- writer, Ben Alderson-Day
- introduction, conversation*
Have you ever had the eerie feeling that there was a presence in your room, even though you were sure you were alone?
If the answer is “yes,” you may be reluctant to admit this experience. Or maybe it was something profound that you happily share with others. Or – more likely – the experience may be somewhere between these two extremes.
Without an explanation to help you process what you experienced, most people have difficulty understanding what happened. But research shows that this ethereal experience is something we can understand using scientific models of mind, body, and the relationship between them.
One of the largest studies on this topic was done in 1894. Published that year by a British entity called the Society for Psychical Research (SPR). Census of Hallucinations (“Census of Hallucinations”, in free translation) – a survey that involved more than 17,000 people in the UK, USA and continental Europe.
The aim of the study was to find out how often people make seemingly impossible visits to announce death. The SPR concluded that these experiences were too common to be the work of chance – one in every 43 people surveyed.
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The strange presence in the empty room may be the person himself
Patrons of the society included former British Prime Minister William Gladstone and poet Alfred, Lord Tennyson.
In 1886, SPR published Phantasms of the Living (“Ghosts of the Living”, in free translation) – a collection of 701 cases of telepathy, premonitions and other paranormal phenomena.
An example reported in the work is the case of Rev. PH Newman of Devonport, Plymouth (England). He told the story of a trip to New Zealand, where a nocturnal apparition advised him to cancel a cruise the next morning. The Reverend later learns that all the passengers on that trip have drowned.
At that time ghost stories were criticized as unscientific. The census was viewed with less skepticism, but still suffered from response bias (only those with something to say would bother to respond to the survey).
But these experiences are present in homes around the world, and contemporary science offers some ideas for understanding them.
Not such a sweet dream
Many of the reports collected by SPR sound like hypnagogia – hallucinatory experiences occurring at the edge of sleep.
Studies have suggested that several religious experiences documented in the 19th century had their origins in hypnagogia. Appearances are particularly strongly associated with sleep paralysis, which affects approximately 7% of adults at least once in their lifetime.
In sleep paralysis, our muscles freeze as REM (rapid eye movement) sleep remains, but our mind remains active and awake. Studies have shown that more than 50% of people with sleep paralysis experience some presence.
Attendance in the Victorian era, documented by the SPR, was often benign or comforting. But modern examples of appearances caused by sleep paralysis often reveal distortions.
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They have stories about nocturnal presence in societies around the world. From Portugal’s Fradinho da Mao Furada to Nigeria’s Yoruba Ogun Oru, who managed to penetrate people’s dreams. His victim is believed to have been bewitched.
But why would an experience like paralysis create a sense of presence?
Some researchers have focused on the specific characteristics of waking up in these unusual situations. Most people find sleep paralysis to be a frightening experience, even without hallucinations.
In 2007, sleep researcher J. Allen Cheyne and Todd Girard argue that if we wake up weak and paralyzed, our instincts will confront us with threats and our minds will fill in the blanks: if we are the victim, there must be a predator.
Another approach is to look for common features between visits during sleep paralysis and other types of presence.
Research over the past 25 years has shown that presence is not only frequent in hypnosis systems. They have also been reported in Parkinson’s disease, psychosis, near-death experiences, and bereavement.
These results indicate that this is unlikely to be a sleep-specific phenomenon.
The mind-body connection
As we know, through neurological case studies and brain stimulation experiments, appearances can be revealed by signals from the body.
In 2006, for example, neurologist Shahar RG and his colleagues were able to produce a “bulge” that was felt by a woman whose brain was electrically stimulated at the left temporoparietal junction (JTP). The image appears to be a reflection of the position of the woman’s body – and JTP combines information about our senses and our bodies.
Several experiments in 2014 also demonstrated that breaking people’s sensory expectations induces a sense of presence in healthy people.
The method used by the researchers tricked people into feeling as if they were touching their own backs, synchronizing their movements with a robot behind them.
Our brain perceives synchronization, assuming that we are creating that sensation. And when the synchronization breaks (making the robot ring slightly out of sync), people can suddenly sense that someone else is present: a ghost in the machine.
A change in the sensory expectation of the situation induces something like a hallucination.
This logic can also be applied to conditions like sleep paralysis. All our normal information about our bodies and our senses is destabilized in this context, so that the feeling that we have “another person” with us is not surprising.
We may think it’s another presence, but it’s actually us.
In all these situations, many aspects of the sense of presence were very similar. The patient felt, for example, that the presence was directly behind him.
All three groups described presence related to sleep, but also presence due to emotional factors such as grief and loss.
Although originating centuries ago, the science of perceived presence is really just beginning. Scientific research may eventually provide us with a comprehensive explanation, or we may need different theories to clarify all these areas of presence.
But the encounters described in Ghosts of the Living are not echoes of a bygone era. If you haven’t had this annoying experience yet, you probably know someone who has.
* Ben Alderson-Day is Professor of Psychology at Durham University, UK.
This article was originally published on the Academic News site the conversation and republished under a Creative Commons license. Read here original version In English.