This article originally appeared in Anomaly 25
All in the mind
The human brain is a far more extraordinary organ than most of us imagine. It is quite capable of manufacturing ‘experiences’ that have no basis in consensus reality. Sadly, for paranormal researchers, some of these effects resemble the kind of phenomena we are attempting to study. Unless we are aware of this possibility our effort may be wasted on purely natural phenomena.
The degree to which the human brain assists in the generation and understanding of paranormal experience has been a hotly debated topic for over a century now.
Sceptics would argue that all paranormal experiences are generated by the scientific workings of the brain and are therefore not ‘paranormal’ but simply cases of misinterpretation. Parapsychologists generally believe that the brain is capable of producing completely unknown powers, such as extra-sensory perception and psychokinesis, which may be involved in a range of paranormal phenomena such as crisis apparitions and poltergeists. Those of a religious or Spiritualist nature will more commonly believe that many paranormal phenomena are generated totally outside the brain through the intervention of discarnate entities such as spirits of the dead, angels or demons. It was partly to try and understand where the seat of such paranormal experience lay that organisations like the Society for Psychical Research and, more recently, ASSAP were founded.
In recent decades the use of technology such as EEGs (electroencephalograph - an instrument that measures brain electrical activity), CAT (computerised axial tomography - a method of producing a detailed cross-section of internal organs such as the brain) scans, computers and sleep laboratories, has allowed the science of psychology to move away from the more theoretical days of Sigmund Freud into an era of measurement and understanding of the way in which the mind and brain work and interact. This process has uncovered a number of now very well documented sets of psychological conditions and disorders that, under the right circumstances, can make a person believe that they are undergoing a paranormal-type experience when in fact they are not.
While psychology cannot explain most of the wide range of strange phenomena that has been documented throughout human history, it can explain some of them. As part of their duty to the understanding of a person’s paranormal experience, it is vital that any investigator be aware of the symptoms and causes of those psychological conditions that can mimic unexplained phenomenon. It is the objective of this section to briefly introduce the investigator to the more commonly encountered of these psychological conditions so that they can be recognised in the field.
This article can only hope to introduce these topics in the briefest of terms. Please use the recommended references for more in-depth reading.
The Common Causes
Sleep Paralysis (The Old Hag)
Symptoms: This disorder is probably responsible for more mistaken reports of the paranormal than any other and it is the most likely to be encountered by ASSAP investigators.
During an episode of sleep paralysis a person will wake to find themselves unable to move any part of the body except, sometimes, their head. This can be accompanied by the feeling that there is somebody else in the room. In extreme cases the person will actually see, hear, smell or even feel a bedroom intruder which normally takes on the form of a supernatural entity from the culture of the victim. Thus sleep paralysis victims in Africa will see demons, those in Europe will see ghosts and Americans will see aliens. The bedroom invader, which is a form of hypnopompic hallucination, can seem very real indeed and may even get into bed with the victim or, more rarely, be reported even to assault them. In conjunction with these hallucinations can come a feeling of immense tightness in the chest area that is commonly described as being like having a heavy weight pressing down on them or like being strangled. It is this description of being pinned to the bed by a weight that is most readily recognisable in supernatural reports that can be attributed to sleep paralysis. After a few minutes the feeling of paralysis, and the supernatural entity, disappear.
Causes: Sleep paralysis was first identified at the end of the last century and has since been induced and studied numerous times under laboratory conditions. Between 15 and 18% of the population have had an attack of sleep paralysis (myself included), normally in their teenage years or in periods of stress, although not always with the associated ‘presence in the room’.
The condition is caused by disruptions to the normal sleep patterns, most particularly the shortening of dream sleep cycles. During dream cycles the body’s muscles are paralysed by the brain to stop people from damaging themselves by acting out their dreams in bed. In the case of sleep paralysis the brain becomes conscious but the paralysis mechanism has not been turned off. The associated feelings of a presence in the room stem from the intrusion of dream sleep into waking consciousness (see Hypnagogic Hallucinations below).
Paranormal Phenomena it Resembles: The symptoms of sleep paralysis can commonly be seen in cases of supernatural assault (including sexual assault), OOBE (out-of-body experience) and alien abduction.
Historically, cases of nocturnal assault by demons (succubi and incubi), vampires, ghosts and witches can all be seen to be derived from sleep paralysis. Some psychologists call sleep paralysis ‘the Old Hag’ after the medieval and Newfoundland traditions of a witch who would paralyse people and sit on their chest during the night. The modern term ‘nightmare’ is derived from the old Germanic word mare meaning incubus.
In the modern world the supernatural entity said to assault the sleep paralysis victim is derived directly from their cultural traditions. Americans get assaulted by aliens, Africans by demons, Europeans by ghosts, south-east Asians by spirits and Newfoundlanders by the Old Hag itself.
The following are accounts of sleep paralysis attacks:
Examples: An ex-nurse from Liverpool claimed to have been sexually molested by a ghost for a period of ten years between 1984 and 1994. She described the attacks as occurring at night and that she would wake up paralysed to find a hooded figure with grey wrinkled skin on top of her. She says that she felt the figure pressing down on her and that she was unable to even scream to attract the attention of her husband sleeping next to her.
A Zanzibar farmer was raped by a local demon called Popobawa. He awoke one night to find himself paralysed. He said:
‘At first I thought I was having a dream. Then I could feel it. Something pressing on me. I could not imagine what sort of thing was happening to me. You feel as if you are screaming with no voice. It was just like having a dream but then I was thinking it was this Popobawa and he had come to do something terrible to me, something sexual. It is [much] worse than what he does to women.’
The following is a quote from ‘Jerry’, an alien abductee patient of Professor John Mack:
‘She [Jerry] woke up terrified and remembered pressure in the abdomen and the genital area and that she could not move. “In my head I was screaming,” Jerry remembers, but does not know if any sound came out.
“Somebody was doing something,” she recalled, but it was “something alien.” Although she recalls wondering to herself, “Is that how sex is done?” she knew with great certainty that “it wasn’t a person.”
In the years that followed, Jerry had a number of “nightmares” in which she would awake paralysed, hear “buzzing and ringing and whirring” noises in her head, and see humanoid beings in her room.’
Further Reading: Hufford (1982); Blackmore (1996, 1998); Chambers (1999).
Symptoms: Hypnagogic/hypnopompic hallucinations occur in the few seconds/minutes before and after sleep. The person will awake, often with a start, to find that they can see, hear, feel or smell something in the bedroom that either disappears or is later found not have happened. The most common hallucinations are: thinking that a name has been called out or that the phone is ringing; bright or dark amorphous blobs that hang in mid-air and slowly fade; a feeling that somebody has touched the face, feet or hands; the appearance of a person by the bedside who rapidly disappears.
Causes: The hypnagogic state is the period when the brain is falling asleep after being awake, while the hypnopompic state is the period when the brain is waking up from sleep. Hallucinations occur, like sleep paralysis, in the confused period of time between sleeping and consciousness when the brain is neither fully asleep or awake. During this time the dream state can intrude into our waking world, producing hallucinations through all the senses. Our brain can also misinterpret signals it receives from the senses and create hallucinations from these as well. For example, a shirt hanging on a wall can, in the first few moments after waking, be misinterpreted as a human figure.
Paranormal Phenomena it Resembles: Hypnagogic/hypnapompic hallucinations are most likely to be misinterpreted as being various types of ghostly phenomena. The paranormal investigator should make a conscious effort to look for reported cases of strange phenomena occurring to people who have just woken up or who are very relaxed or falling asleep.
The chances of seeing a ghost are greatly enhanced if the person is sitting or lying down and in a relaxed state. Similarly, a majority of the several hundred cases of crisis apparition collected in Phantasms of the Living occurred to people who had just woken up. This is not to say that there may not be a paranormal element in some of these cases (eg. telepathy), but the link with hypnagogia/hypnopompia is quite unmistakable.
Examples: Bob is a person, encountered by the author, who has a severe fear of spiders. He does not interpret his experience as being in any way paranormal and recognises it as a hallucination.
‘I woke up suddenly and saw a massive spider run across the top of my duvet and onto my pillow. I sat straight up in bed and shouted.... Although I knew it wasn’t real [he has had a similar experience on a number of occasions] I still had to strip the bed back to its mattress and wake up my flat mate to check the room.’
‘On the second night, at about 4.00am when I was almost fast asleep, I heard a loud purring noise and felt a pawed animal walking across my chest and abdomen, like a heavy cat. I was mostly asleep, so I convinced myself that it was part of a dream and did not open my eyes to look.’
Symptoms: A person is concentrating on something so hard that they may become totally unaware of anything else that is going on around them. This can occur, for example, while driving a car, watching television, reading or any other single-minded task. In the absorbed state a person may be so engrossed as to be completely unaware of passing time or of the actions of others around them. Once the concentration is broken, the person may be surprised to find out what has happened during their absence. For example, a motorist may not remember large sections of a car journey he has just undertaken. Many complain of a feeling of lost time. Absorption can also be associated with certain drug states and with repetitive tasks such as rhythmic dancing.
Causes: Absorption is a function of the mind’s ability to devote itself solely to one task to the exclusion of all others. It is also the ability of the mind to ‘switch-off’ during repetitive actions.
Paranormal Phenomena it Resembles: Many of the results of absorption can be seen in UFO encounters involving motorists late at night. Alien abductees commonly report that they have missing periods of time when driving home and that they may suddenly ‘wake-up’ to find themselves several kilometres from where they can last remember driving. Both these are common results of periods of absorption which, combined with the human tendency to underestimate the length of time a journey will take, can make it feel like a journey has taken longer than it should and that sections of it have been erased from the memory. Linked with this is what Jenny Randles has called the ‘Oz factor’ where, during a paranormal encounter, all external stimuli seem to disappear, eg. birds stop singing, other traffic disappears from the road, etc. This, too, has the hallmarks of absorption.
Laboratory tests have found that a capacity for absorption varies considerably between people. High absorption capacity has been linked to a tendency for fantasy proneness, something else that may strengthen this condition’s link to the paranormal.
Examples: The following case, which happened to Elsie Oakensen of Northamptonshire in November 1978, has many hallmarks of absorption. Elsie was on the busy A5 road in daylight when she saw some lights in the sky and then a UFO.
‘When I got off the A5 the electrics of the car started to play up. I was able to travel a little further, until I passed under some trees. When I came out from under the trees I suddenly found myself in darkness, absolute pitch black darkness. As I sat in the car I could not see the road, buildings, trees or anything else.
As I sat there, a circle of brilliant white light about a yard in diameter shone onto the road to the left-hand side of the car. It went off and it was dark again.’ This occurred several times before Elsie suddenly found herself ‘...in normal daylight about thirty yards down the road, driving normally in third gear as I had been before this started. I travelled for about a hundred yards without being in control of the car. I think it was probably being driven by remote control.’
Folie à Deux (Contagious Insanity)
Symptoms: Two or more people, who are often related to one another or share some aspects of their lives together, may develop shared delusional beliefs, suspicions or paranoia.
Causes: In cases of folie à deux there is normally one very dominant person who imposes their psychotic beliefs onto the other person(s). This often happens in conditions where the people have, deliberately or otherwise, isolated themselves from normal human contact. Many psychologists have studied this disorder in an effort to understand how madness can spread from person to person.
Paranormal Phenomena it Resembles: Folie à deux is a relatively rare condition that is unlikely to be encountered by many ASSAP members. Its greatest effect has been seen in cults where a charismatic leader can impose his beliefs and laws onto his congregation sometimes, as with the Heaven’s Gate cult, with disastrous consequences. It has been postulated that a minor form of folie à deux could be operating in situations where multiple witnesses have observed a paranormal phenomenon. For example, C. D. B. Bryan carries examples of multiple-alien abductees who have, through over-analysis of a probable example of absorption, convinced each other that a shared paranormal event had taken place.
Examples: A French convent in the early nineteenth century had an outbreak of mewing nuns. The trouble started when one nun began to continuously mew like a cat. She was soon joined by other nuns until practically the entire convent would spend their entire day standing in the courtyard mewing. There are many, many other historical examples of such convent madness including, most famously, the Devils of Loudun. Convents, by their isolated communal living and devotion to routine, are ideal candidates for folie à deux.
The Sense of Presence
Symptoms: A person on their own will become aware that they are not alone. They may believe that they are being followed, that they are being watched or that the atmosphere around them has become oppressive and unpleasant. Accompanying this may be perceptions that the environmental conditions around them have changed, eg. they may believe it has become suddenly dark, cold or quiet.
Causes: The individual causes of a person’s believing they are not alone are manifold, but it is essentially a mild form of paranoia brought on by the person’s being uneasy about the location they are in. In such circumstances it can be easy for the mind to convince itself that its worst fears are coming true.
Paranormal Phenomena it Resembles: A sense of presence sometimes forms a large part of reported cases of paranormal phenomena where very little is actually witnessed. Many haunted houses are designated so by virtue of an owner or visitor, who will normally claim to be sensitive to such things, feeling that there is an ‘atmosphere’ about the place. Sometimes entire reports can consist of nothing but a feeling of unease by the witness (see below). It is also possible that the perceived drop in temperature or uneasy quietness associated with hauntings could be related to this condition. Some first-hand examples of phantom hitchhikers also consist of little more than a feeling of a supernatural presence in the car or, in some cases, on the back of a motorbike.
Examples: ‘A reporter of the Marlborough Times whose home was in Ogbourne St. Andrew was in the habit of travelling to and from Marlborough each day. He noticed when he came to a certain spot in his journey he always felt very cold, regardless of the weather and also felt some “presence” in the car... At a certain spot it left the car, after which the temperature returned to normal.’
‘When this man went to see his girlfriend, he had to walk through a swamp to get to her house. One night he stayed rather late, and when he came back through the swamp, he heard something following him along the edge of the road. When he looked he could see nothing, and when he walked it walked, and when he ran it ran. He said that when he got to the edge of the swamp, the sound stopped in some weeds at the edge of the road. He picked up a rock and threw it into the weeds, but no sound came from the side of the road.’
Diminished Input (Sensory Deprivation)
Symptoms: People who are on their own for long periods of time, or who are performing repetitive tasks, can suddenly find themselves experiencing hallucinations that resemble paranormal phenomena. Most common are the sudden arrival of ‘spectral companions’ or of solid-looking people. However, voices, tactile feelings, smells and tastes can also result.
Causes: Psychical researchers have long recognised the value of diminished input to the paranormal. Some laboratories believe that depriving people of key senses like sight and sound can help enhance the psychic senses. The Ganzfeld experiments use a mild form of sensory deprivation and have allegedly produced significant positive results in tests for extrasensory perception.
Diminished input, in the form of isolation from other human beings, is also capable of producing false sensory information that resembles paranormal phenomena. The sense of presence discussed earlier is a mild form of this; a stronger reaction is the hallucination and pseudo-hallucination (a hallucination that is realised to be unreal by the perceiver).
Hallucinations can come in a wide variety of forms of differing intensity. They can be auditory, tactile, visual, olfactory or any combination of these things. They can be produced by a massive range of conditions, not just diminished input, and are also associated with drugs, illness (physical and psychiatric) etc. - these latter causes are beyond the scope of this article.
Diminished input in the form of loneliness, hunger, tiredness, repetitive tasks and illness can lead to altered states of consciousness in which day-dreams and hallucinations can seem very real indeed. Total sensory deprivation, in the form of isolation tanks, can lead to much more extreme hallucinations involving wild flashing lights, whole imaginary landscapes and the appearance and disappearance of spectral people and/or supernatural beings.
Some religions utilise diminished input to induce paranormal-type phenomena. For example, social isolation (eg. hermits), starvation, repetitive tasks (eg. chanting, ritual prayer, counting), rhythmic dancing or meditation. All these can induce altered states of consciousness in which the person believes they are having a divine experience.
Paranormal Phenomena it Resembles: Pseudo-hallucinations are a common side-effect of diminished input, particularly in conjunction with tiredness. Those people who spend long periods of time on their own (eg. deep-sea divers, lone explorers, long-distance drivers, hostages, single-handed yachts-people, mountaineers, etc.) are particularly susceptible.
A large proportion of paranormal phenomena occur to individuals who are on their own. Lone drivers are particularly susceptible, and there is a whole range of phenomena that are associated with people driving on their own at night - phantom hitchhikers, spectral jaywalkers and alien abduction to name but a few. Lone walkers also report encounters with black dogs, ‘white ladies’ and other ghostly phenomena. Solo mountaineers, divers, yachts-people, explorers and hostages sometimes find themselves with very solid-looking companions whose existence they know is not real.
Examples: ‘The lone sailor Joshua Slocum was smitten with sea-sickness in the middle of the South Atlantic and could not leave his cabin for several hours. When a storm blew up, a phantom helmsman appeared and took control of the vessel. Slocum had a long conversation with him, and was told that his visitor was the pilot of one of Christopher Columbus’ ships.’
Scuba instructor Ian Skinner was diving off Malta when ‘..I saw a light ahead of me and was drawn towards it both by curiosity and what seemed like an unknown force. Over the next ridge and very much further down I saw a very beautiful young woman, tall and slim, with a lovely figure, standing at the entrance to a large cave... I thought I must be suffering from nitrogen narcosis... then she spoke: “Hello, I have been waiting for you, do not be afraid, with me you are safe.” I backed away but she smiled, walked towards me and held out her hand. It felt warm, sensual and safe, and my fear disappeared.
“When you return to me I will be waiting for you, then you will stay with me for ever. I have a gift with you.” She handed me a small jar shaped like an amphora. As I ascended, I saw her waving as she slowly faded from view.’
Symptoms: A person will see a life-sized mirror image of themselves standing just beyond their reach. This image will often replicate the living person’s movements but is normally transparent, blurry or lacking any colour. Such encounters normally take place during the night or at dawn. The very rare negative autoscopy involves people who cannot see their reflection in mirrors, etc. Most encounters are of only a few seconds’ duration.
Causes: Autoscopy is associated with periods of stress, tiredness or mental illness. Its study is not well documented and most examples of it have been associated with schizophrenia, delirium or epilepsy. It can also be experienced by people not suffering from these mental illnesses, where it is normally associated with diminished input or extreme forms of stress, including migraine headaches.
There may be a comparison between autoscopy and the ‘phantom limb’ syndromes suffered by amputees and also the ‘Alice in Wonderland’ syndrome where people’s perspective about the shape and size of parts of their body becomes confused.
Paranormal Phenomena it Resembles: Autoscopy is synonymous with the paranormal tradition of the dopplegänger, where a person has an encounter with their own ghost (sometimes called a fetch). The term dopplegänger was taken from the German folk-belief that seeing your own double is an omen of death. The association of autoscopy with severe brain injury and brain tumours may well be the cause of this myth. People can also see images of their own body during near-death and out-of-the-body experience, although these are not traditionally classified as examples of autoscopy.
Negative autoscopy, or the inability to see one’s own reflection, is rare (so rare that I have not encountered any examples of it in the literature!), but there is an obvious resemblance to the lack of reflection attributed to vampires. Whether there is any relationship or not is not known.
Examples: ‘On the 15th March, 1978, at 10 o’clock at night, I saw an apparition of myself. I was alone... One of the children was sleeping restlessly; I took the lamp to see if anything was wrong. As I drew back the curtain which shut off the bedroom, I saw two paces from me the image of myself stooping over the end of the bed, in a dress which I had not been wearing for some time: the figure was turned three-quarters away from me, the attitude expressed deep grief...’
Beyond the Scope of this Article
The are some extremely complex and contentious psychiatric conditions with paranormal implications that cannot reasonably be covered here. I would urge those interested to familiarise themselves with the following:
Dissociation of the Personality
People suffering from multiple personality disorder (also called dissociative identity disorder) can apparently have several different personalities living within the one body. Each of these personalities may be of a different age, sex and temperament to the others. Although its existence is still very hotly debated, patients with this disorder show a remarkable resemblance to the multiple personalities displayed by Spiritualist mediums and those possessed by spirits.
There are a number of psychiatric conditions that are integrally tied into the religious or cultural beliefs of the individual. Speaking in tongues (glossolalia) is almost exclusively restricted to evangelical Christian communities. Koro, where the patient believes his penis to have retracted into the body, is a Chinese cultural belief (although it has recently occurred in West Africa). Latah is a southeast Asia condition where a person exactly mimics the actions and movements of another.
Cryptomnesia (Hidden Memories)
There is a strong belief among some psychiatrists that the brain can deliberately hide memories of violent or abusive episodes in a person’s life. These memories are frequently recovered using hypnosis and have been used on occasion as evidence of physical and sexual abuse in court cases.
The scientific value of such techniques has become increasingly doubtful of late and there is considerable evidence that, instead of recovering memories, hypnosis actually implants them, leading to so-called false memory syndrome. The value of evidence obtained through hypnosis is now uncertain, which has implications for the testimonies found in examples of past-life regression, alien abduction, Satanic ritual abuse, multiple personality disorder and others.
Paranoid delusions of grandeur and persecution can become complex and unpleasant affairs. Overlap into the paranormal can occur when the paranoid delusions are fixated upon conspiracies in which the individual is at the centre of a plot by larger organisations such as governments, religions or big business. Paranoid people may be predisposed to believe in conspiracy theories, and there are several extreme delusional states, such as Capgras Syndrome (illusion des sosies), in which it is believed that objects, close relatives or whole societies have been replaced by sinister carbon copy replicas.
Although a commonly used term, fantasy proneness is actually poorly defined. It is apparently possible to define people’s fantasy proneness using a series of psychological tests. Those with a higher fantasy proneness index are liable to have imaginary childhood friends and to have lived in make-believe worlds. Fantasy prone people are statistically more likely to report having paranormal experiences and have an increased capacity towards absorption and hypnosis. Near-death, out-of-the-body, UFO and ESP experiences have all been linked to fantasy proneness, as have mediumship and religious visionary experiences.
This brief article has been designed to introduce the most commonly encountered psychological and psychiatric disorders that may be mistaken for a paranormal experience. This list is not by any means definitive and each topic has only been covered in the scantiest of detail - those who are interested should consult some of the books in the further reading list or try searching the Internet.
When reading about peoples’ paranormal experiences, or interviewing them in person, some of the above symptoms may become apparent. Pay particular attention to paranormal experiences that occur to people when in bed, when driving at night or when alone in a potentially ‘spooky’ location (eg. an empty house). These are just the conditions that are liable to produce an anomalous experience through optical illusion, hallucination or other cognitive means. Although it is good to be aware of these conditions, it is irresponsible to try and make amateur diagnoses of genuine psychiatric and psychological disorders - something to bear in mind for those ASSAP investigators that will have to interview people about their experiences.
We can only ever hope to try and understand peoples’ strange experiences through painstaking investigative work and through a thorough understanding of both the workings of psychology and parapsychology. Often these experiences are explicable in rational terms. However, sometimes a rational solution is not possible and the experience can be considered genuinely paranormal. At this point science will normally turn its back on such experiences and it is then left to organisations such as ASSAP to make sense of them.
A bizarre but seemingly quite natural effect was recently reported in New Scientist (July 1999). Strangely, it has never been studied scientifically. It is the phenomenon of suddenly perceiving everything miniaturised. It might be likened to looking at the world through a pair of binoculars from the wrong end. The suggested explanation is that the mechanism that the brain uses to scale objects suddenly gets it wrong. This perfectly natural mechanism is the one that makes a moon on the horizon look much bigger than one overhead. The brain compares the size of the moon on the horizon with terrestrial objects like trees and decides it is bigger. Such an effect, which appears spontaneously and suddenly, could easily be misinterpreted as paranormal (as an OOBE for instance). Ed.
Paul Chambers would like to hear from anyone who has had, or knows someone who has had, first hand experience of any of the phenomena described in this article. Please email him with reports on: firstname.lastname@example.org
Some places tend to attract more reports of paranormal activity than others. Such 'haunted places' may gain their reputation through psychological, rather than paranormal, means.
- Chambers, P. Sex and the Paranormal. Blandford Press (London), 1999.
- Evans, H. Visions, Apparitions, Alien Visitors. Thorsons Publishing (London), 1984.
- George, L. Alternative Realities . Facts on File (New York), 1995.
- Gregory, R. L. The Oxford Companion to the Mind. Oxford University Press (Oxford), 1987.
- Hufford, D. J. The Terror That Comes in the Night. University of Pennsylvania Press (Philadelphia), 1982.
- Reed, G. The Psychology of Anomalous Experience. Prometheus Books (New York), 1988.
- Townsend, M and Hope, V. The Paranormal Investigator’s Handbook. Collins and Brown (London), 1999.
- From an interview done by the author.
- The Paranormal Review , Issue 10, p.30, 1999.
- Spencer, J. The UFO Encyclopedia. Headline, 1997. p.268-9.
- Bryan, C. D. B. Close Encounters of the Fourth Kind. Weidenfeld & Nicolson, 1995. Chapter XIII.
- Wiltshire, K. Ghosts and Legends of the Wiltshire Countryside. Compton Russell Ltd., 1973. p.39.
- Montell, W. L. Ghosts Along the Cumberland. University of Tennessee Press, 1987. p.118.
- Reed, G. The Psychology of Anomalous Experience. Prometheus Books, 1988.
- Fortean Times , Issue 92, p.51.
- Parish, E. Hallucinations and Illusions. Scott, 1897. Quote taken from Evans, H. Visions, Apparitions, Alien Visitors. Thornsons, 1984. p.62. NOTE: the 1978 date, which is reproduced from Evans, does not tally with the year of the original book which was published in 1897.