The Human Truth Foundation

Hallucinations, Sensory Deprivation and Fasting
The Physiological Causes of Religious and Mystical Experiences

By Vexen Crabtree 2015

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#bahá'í_faith #buddhism #christianity #epistemology #experience #god #psychology #religion #subjectivism #taoism #thinking_errors

Hallucinations caused by eye problems can result in surprisingly specific visions of grotesque faces with large eyes and teeth, blood running upwards, and costumed figures1 as our brain tries to interpret errant inputs2. But most hallucinations start in the brain and most of them are subtle and not just a matter of visual phenomenon. Disease, neurochemical imbalances, fasting, exhaustion, sleep and sensory deprivation3,4, chanting, practices of austerity and ritualistic behaviour can all induce hallucinations and other strange states of mind5. They can also be triggered artificially by doctors. The range of experiences produced is varied, from mundane events such as smelling something to out of body experiences. Experimenters can consistently generate deeply meaningful religious experiences which would be utterly convincing if participants didn't know it was being generated artificially. People interpret these episodes in terms of their local culture - Western Christians don't receive Buddhist enlightenment and witness their previous lives, for example, whilst Eastern Daoists don't receive images of the Virgin Mary6. For those who know no neurology it is easy to see how supernatural beliefs can result from such episodes.

A wide variety of religious customs and beliefs across the world are clearly the result of misunderstood biology5. Native American tribes considered fasting being the way for receiving guidance from the Great Spirit. Moses fasted for forty days on Sinai while "talking to God" - the result was the 10 Commandments (Exodus 34:28), Elijah fasted forty days as he journeyed to Horeb, where, in a cave, he experiences a range of effects (1 Kings 19:8-15) and Bahá'u'lláh, (of the Bahá'í Faith) received revelations after spending months in a black underground prison. Jesus also fasted 40 days and as a result, experienced a battle with Satan in a series of visions (Matthew 4:1-11). As a species, we have been artificially inducing mystical experiences for as long as there are records of our behaviour, although nowadays we have a much better understanding of the underlying neurology and how it effects our consciousness.

1. People Have False Experiences

#beliefs #consensus #delusion #epistemology #expectations #experiences #god #illusion #religion #subjectivism

People can experience things which are convincing to them, but, which are not based on reality. An extract from "The False and Conflicting Experiences of Mankind: How Other Peoples' Experience Contradict Our Own Beliefs" by Vexen Crabtree (2008):

There are many neurological and physiological causes of odd experiences in our lives. These range from ordinary tricks of the eye1 through to repeated minor epileptic fits that cause nothing more than visual hallucinations combined with emotional cues. Strange and unusual experiences often give rise to strange and unusual beliefs7 especially for those people are not inclined towards finding natural explanations for events. Experiments have found that a person's "psychological tendencies may also be used to predict exact types of 'unexplained' phenomena in which they are likely to believe" and that those who display signs of dissociation are likely to see "a given stimulus item as a paranormal creature, whether Bigfoot or an alien"8.

For example during night terrors, our brain is still suppressing bodily movement and it feels we're being forced down on to the bed, complete with much anxiety and fear. Some people have such attacks multiple times. The belief that this is a demonic attack seems natural to many and even after explaining the physiological and natural causes of night terrors, many continue to believe in a supernatural source. Of course, this is ridiculed by those who know that such attacks are really alien investigations of the Human body. Both explanations are foiled however by neuroscientists who understand that the cause of these experiences is biochemical in nature.

Cultural expectations play a large part in the interpretation of personal events, meaning that the resultant beliefs vary according to geographical region. We all find rational arguments to explain away those who experience things that contradict our own interpretation of reality - in secret, when we find people who have experienced things that we don't believe in, we all think we can explain others' experiences better than they themselves can explain them. Investigations into the physiological causes of strange beliefs comes from an ancient line of skepticism. In "The Supernatural?" by Lionel A. Weatherley (1891) the author intelligently outlines many such investigations - and that was well before modern neurology started making its amazing strides towards understanding the sources of experiences. Despite this knowledge, the masses remain generally unconvinced, and stick to ages-old cultural and subjective beliefs. The Christian Pentecostals have a saying, "the man with an experience is never at the mercy of the man with a doctrine"9, meaning that rationality subverts itself to experience. In total, we cannot entirely trust our experiences nor those of others, and more careful investigation is needed by all.

"The False and Conflicting Experiences of Mankind: How Other Peoples' Experience Contradict Our Own Beliefs: 1. Introduction" by Vexen Crabtree (2008)

Clearly the range of Human experience gives rise to many contradictions. Not all experiences can be entirely true. We know that the evident facts are sometimes not quite so factual. We have all experienced things that actually did not happen. We have dreamt, tripped, imagined and forgotten things leading us to conclusions and sternly felt beliefs in things that are not real.

2. Hallucinations

Hallucinations are the biggest cause of strongly held supernatural beliefs. Contrary to popular opinion, hallucinations are not particularly rare and they are not the reserve of a few odd people. Most people have hallucinations at some point. Eye disease and medical problems with the eye can lead to a surprisingly specific range of hallucinatory experiences, including seeing (in particular) grotesque faces with large eyes and teeth, costumed figures, various patterns, and Dr Ffytche who has headed up scientific investigations on this topic, "believes the narrow repertoire of images seen in hallucinations is related to the way visual systems are organised in the brain [and he] suggested that sightings of ghosts and near-death experiences could have the same biological cause"1.

Many hallucinations start in the brain, rather than in the eye. They can involve all the senses; sight, sound, touch, taste, although most the time an episode involves just one sense. Some go completely unnoticed. Some are vague; some are very specific. Some feel real and some do not. They can be caused by epileptic fits (including ones that have no impact on the rest of the body), problems with blood sugar and nutrition, illness, exhaustion, mental stress, and by a wide range of hallucinogenic drugs. They can also be triggered artificially using electrodes on the surface of the brain or deeper within it, and, what we know from many such studies is that the range of experiences produced by abnormal stimulation of neurones is incredibly varied, involving mundane events such as smelling something, to out of body experiences and strong religious experiences. The fact that such experiences can result from the stimulation of the brain is profound, and is a serious piece of evidence against the idea that we require souls to explain consciousness, or that the underlying cause are external spirits or gods.

A range of hallucinations that result from Charles Bonnet syndrome are of the kind that feel "forced upon" sufferers with no sense of familiarity or emotion10. It feels that they come from an external source - such as a telepathic human or spiritual ancestor, an angel or demon, or from aliens. These forms of hallucinations have formed the bedrock of many-a-mystics repertoire of tales, and even, through active individuals, resulted in the foundations of entire religions.

3. Artificially Inducing Mystical Experiences of God11

#atheism #christianity #USA

By 2002 Dr Persinger had tested a theory on 2,000 patients, subjecting them to a weak magnetic field to their right hemisphere (or to both hemispheres), and monitored results with an EEG. This was performed in particular on patients who had experienced above-average numbers of epileptic episodes. 80% of them had various kinds of supernatural experience which were "so profound they would be life-changing had they not understood the mechanistic underpinnings of what they had experienced". The experiences included visions of Jesus Christ, Elijah and the Virgin Mary, prophet Mohammed or a Sky Spirit, depending on their cultural background. They also had out-of-body experiences, some felt they were floating, and many had a feeling of great meaningfulness associated with the event.12

Dr. Mario Beauregard of the University of Montreal, USA, done further experiments in 2006, including placing 15 nuns into an MRI machine and inducing mystical experiences. Comparing their feelings and experiences to other groups of people, he concluded that "if you are an atheist and you live a certain kind of experience, you will relate it to the magnificence of the universe. If you are a Christian, you will associate it with God"6.

In short, they had visions and mystical experiences that they would otherwise think were real if they didn't know it was artificially induced. We know that electromagnetic activity in the brain is absolutely tied up with our own self, thoughts and consciousness, and this is further evidence (aside from history, psychology, etc) that the experience of many mystical things and god has a basis in physiological cause and effect, with the physical cause preceding the experience. Epileptics and other experiments have also shown that temporal lobe imbalances cause distortions in our perception of reality. People with increased temporal lobe sensitivity experience stronger and more profound events during similar experiments. It is very telling that a person's existing knowledge causes them to interpret their feelings in radically different ways: it is clearly their brain that is priming the episode, with the content coming from the brain itself and not via a mystical conduit to a supernatural realm.

4. Fasting, Sensory Deprivation and Religion


Hallucinations can be caused by our own behaviours and lifestyle. This includes fasting, sensory deprivation, chanting and other related practices of austerity, often undertaken by those actively seeking religious experiences.5

Others consider fasting in earlier cultures to have arisen as a result of the discovery that it could induce a state of susceptibility to visions and dreams. [...] Within some of the mystery cults, fasting was incorporated as part of the ritual preparation for the incubation sleep that, by means of dreams, was to provide answers to specific questions and needs of the person.13 [...] Both Greek philosophers (e.g. Pythagoreans and Neoplatonists) and Hebrew prophets believed that fasting could produce trancelike states through which revelations would occur. Plutarch narrates how the priests of ancient Egypt abstained from meat and wine in order to receive and interpret divine revelations14 and Iamblichus tells how the prophetess fasted three days prior to giving an oracle15. [...] According to Philo Judaeus (25 BCE-50CE), the Therapeutae, a group of Jewish contemplatives living in community, fasted as a means of purifying the spirit so that it could turn itself to more spiritual activities such as reading and study.

"The Encyclopedia of Religion" by Eliade Mircea (1987)5

Full sensory deprivation is a situation where we sit in extreme silence, darkness and extreme quiet for extended periods of time. It very rapidly becomes highly uncomfortable and results in all kinds of hallucinations and strange experiences. Our brains are simply not wired to cope with low levels of external input. Psychological experiments on sensory deprivation chambers show shocking and dramatic results. Ten days in such a chamber (the same as with sleep deprivation) results in serious and permanent psychological damage. But on less severe experiments, the chambers were modified so that the analyst could speak, at times, to the subject. The suggestibility of the subject was akin to hypnotism, only much more effective, with the subject being aware of and remembering everything that is said, but also finding themselves uncontrollably agreeing after only a day in the sensory deprivation chamber. The same effects can be achieved with less complete setups, with periods of mild sensory deprivation being a facilitator of self-induced religious experiences.3,4

A clear example can be found in the founding stories of The Bahá'í Faith. It was the year 1852 and Bahá'u'lláh found himself imprisoned "in a subterranean dungeon in Teheran's notorious Siyáh-Chál, the 'Black Pit' [...]. It was in this dungeon that Bahá'u'lláh received His revelation". Bahá'u'lláh describes the horrible dungeons that caused these hallucinations, and we can see they are clearly similar to sensory-deprivation conditions: "We were consigned for four months to a place foul beyond comparison. The dungeon was wrapped in thick darkness, and our fellow-prisoners numbered nearly a hundred and fifty souls [and] it had no other outlet than the passage by which We entered". All kinds of fevers and delusions overcome people in such situations. In keeping with what we expect, Bahá'u'lláh described the moment that his revelations began: "The breezes of the All-Glorious were wafted over Me, and taught Me the knowledge of all that hath been".16. On the basis of this, he became the prophet and founder of an entire new religion.

Such basic science and physiology explains a wide variety of religious customs and beliefs across the world. Mircea documents how Native American tribes considered fasting being the way for receiving guidance from the Great Spirit. Moses fasted for forty days on Sinai while "talking to God" - the result was the 10 Commandments (Exodus 34:28), After a final meal, Elijah also fasted forty days as he journeyed to Horeb, where, in a cave, he experiences a range of effects, including a commandment about who is to be future king of Syria (1 Kings 19:8-15). Jesus also fasted 40 days and as a result, experienced a battle with Satan in a series of visions (Matthew 4:1-11). As a species, we have been artificially inducing mystical experiences for as long as there are records of our behaviour.

Current edition: 2015 Nov 2517
Parent page: The Human Truth Foundation

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References: (What's this?)

Skeptical Inquirer. Magazine. Published by Committee for Skeptical Inquiry, NY, USA. Pro-science magazine published bimonthly.

The Economist. Published by The Economist Group, Ltd. A weekly newspaper in magazine format, famed for its accuracy, wide scope and intelligent content. See for some commentary on this source..

The Bible (NIV). The NIV is the best translation for accuracy whilst maintaining readability. Multiple authors, a compendium of multiple previously published books. I prefer to take quotes from the NIV but where I quote the Bible en masse I must quote from the KJV because it is not copyrighted, whilst the NIV is. Book Review.

Boyer, Pascal
(2001) Religion Explained. Hardback book. Published by William Heinemann, Random House Group Ltd, London, UK.

Eliade, Mircea
(1987, Ed.) The Encyclopedia of Religion. Hardback book. Published by Macmillan Publishing Company, New York, USA. 16 huge volumes. Eliade is editor-in-chief. Entries are alphabetical, so, no page numbers are given in references, just article titles.

Gregory, Richard L.
(1987) The Oxford Companion to the Mind. 1987 reprint. Published by Oxford University Press, Oxford, UK.

Kaku, Michio. Professor of theoretical physics.
(2014) The Future of the Mind. E-book. Subtitled: "The Scientific Quest To Understand, Enhance and Empower the Mind". Amazon Kindle digital edition. Published by Penguin Books Ltd, London, UK.

McConnel, James V.
(1986) Understanding Human Behavior. Hardback book. 5th edition. Originally published 1974. Current version published by CBS College Publishing, Holt Rinehart and Winston, New York, USA.

Sheppherd, Joseph
(1992) The Bahá'í Faith. Paperback book. 1993 reprint. Published by Element Books Ltd, Shaftesbury, Dorset.

Weatherley, Lionel A.
(1891) The Supernatural?. Hardback book. Published by J. W. Arrowsmith, Bristol, UK. This is a hard to find book. Bath Library has a copy, accessed 2012 Dec 14.


  1. BBC News (2000 Sep 11) accessed 2000 Sep 14.^^^
  2. Two specific causes of such wild interpretations are the pareidolia effect (the seeing of patterns in random data) and the HADD (Hyperactive Agent Detection Device - the way we first and foremost look out for other sentient beings). For more of these, see: Errors in Thinking: Cognitive Errors, Wishful Thinking and Sacred Truths.^
  3. McConnel (1986) p251-253.^^
  4. Gregory (1987) entry on Isolation Experiments.^^
  5. Eliade (1987) Volume 5 entry "Fasting".^^
  6. Kaku (2014) chapter 9, "Altered States of Consciousness", digital location 3270-3287.^^
  7. Boyer (2001) chapter 1 "What is the Origin?" p6-7 Pascal states that one of the appeals of religion, according to many, is that 'Religion explains puzzling experience: dreams, prescience, etc'.^
  8. Two studies reported in Skeptical Inquirer (2012 Jul/Aug): Matthew J. Sharps article "Eyewitness to the Paranormal: The Experimental Psychology of the 'Unexplained'", p39.
    • Sharps, M.J., J. Matthews, and J. Asten (2006). "Cognition, affect, and beliefs in paranormal phenomena: Gestalt/feature intensive processing theory and tendencies towards ADHD, depression, and dissociation" in the Journal of Psychology 140(6):579-90.
    • Sharps M.J., E. Newborg, S. Van Arsdall, et al. (2010). "Paranormal encounters as eyewitness phenomena: Psychological determinants of atypical perception interpretations" in Current Psychology 29(4):320-27.
  9. The Economist (2006 Dec 23) p85.^
  10. Skeptical Inquirer (2013 May/Jun) article Oliver Sacks on Hallucinations: An Interview by Indre Viskontas p49-53.^
  11. Added to this page on 2003 Mar 28.^
  12. Ontario Consultants on Religious Tolerance on, accessed 2002 Dec 04.^
  13. Article refers to Philostratus (c. 170-245 CE) in Life of Apollonius 2.37.^
  14. Article refers to Plutarch Isis and Osiris 5-6^
  15. Article refers to Iamblichus Egyptian Mysteries 3:7.^
  16. Sheppherd (1992) chapter 4 "The Birth of the Baháí Revelation" p29-30.^
  17. 2015 Nov 25: Based on text dating from 2002 Dec 04^

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