Entoptic Imagery and Altered StatesEntoptic images are visual effects which originate within the visual processing system of the observer.  The term ‘entoptic’ comes from the Greek for ‘within vision’, indicating that the images come from anywhere within the optic system, between the eye itself and the neural cortex where signals from the optic nerve are interpreted.  Since it originates within the visual system, entoptic imagery can only be seen by the observer.

For clarity, I would like to include a quick note on the definition of entoptic imagery.  In their discussion of paleolithic cave imagery, Lewis-Williams and Dowson define entoptic imagery as visual experiences arising from anywhere within the optic system, which includes the eyes, the occipital lobe of the brain, and the many other portions of the neural cortex that process visual stimuli.  This definition comes from the Greek translation of entoptic meaning “things perceived within vision”, and is commonly used by anthropologists and archaeologists (Williams & Dowson 1988).  On the other hand, in most medical literature, entoptic imagery is defined as imagery which only originates from within the eye itself.  Given the Greek meaning of the word entoptic, I prefer the anthropological definition of the term.  Therefore, for the purposes of this article, ‘entoptic’ indicates imagery that arises from anywhere within the visual system, from the eyes to the neural cortex.

Types of Entopic Images

There are a variety of types of entoptic images which originate in different parts of the visual system.  Some of the most well understood entoptic effects originate within the eyeball itself.  These include floaters, which are formations of protein clumps in the vitreous gel of the eyeball that can be seen when looking at a bright, blank background such as the sky;

and Purkinje trees, which are images of the retinal blood vessels in one’s own eyes that can be seen when a light is shined into the periphery of the eye.
Purkinje Tree

Another type of entoptic imagery that you may be familiar with is known as a phosphene.  Phosphenes occur when the individual perceives light when there is no light entering the eye.  Phosphenes can be caused by a variety of factors.  For example, gamma rays from space sometimes impinge on the retina and cause the individual to perceive flashes of light.  Individuals who go for a long time without visual stimuli will also sometimes see phosphenes in the form of light and images.  These sorts of phosphenes seem to be produced beyond the eye, in the visual cortex. This phenomenon has been given the nickname ‘prisoner’s cinema’.  In some Tibetan traditions, monks do a practice known as dark retreat in which they meditate for long periods in a pitch black room.  They say that after some time, lights and images arise in front of their eyes.  These images would also be defined as phosphenes, and it is clear from descriptions that they also hold a great deal of spiritual meaning (Rosenshein 2011).

Another type of entoptic imagery, called a ‘form-constant’ by some scholars, is also produced beyond the eye in the visual cortex.  These images are generally geometric in pattern and originate in the nervous system.  They may be interpreted and enhanced by the observer as a particular image or pattern, in which case they are considered visual hallucinations.  These phenomena can easily be seen by the observer, but cannot be seen at all by anyone else.  Images such as these are often observed in altered states brought on by the use of entheogens, trance states induced by meditation, fasting, drumming, and so forth, and by imbalanced brain states in individuals suffering from mental diseases such as schizophrenia (Lewis-Williams & Dowson 1988).

If you are still unsure as to what exactly an entoptic image is, try closing your eyes – after a few moments, if you pay attention, you will begin to perceive vague colored lights. You can even induce these lights by closing your eyes and pressing gently on the sides of the eyeballs, or by squeezing your eyes shut very tightly.  The exact cause of these effects is not known – perhaps they are random firings of neurons within the visual system – but we do know that they are common to all humans.

Once entoptic images originate within the visual system they are interpreted by the visual cortex, which receives signals from the eye and produces secondary signals that allow the rest of the brain understand the image.  These entoptic images have been interpreted in many different ways by different cultures and peoples all over the world.  All human beings experience the same entoptic images, but they may interpret them in different ways depending on the traditions they have been exposed to and the methods they use to perceive the world.  Studies on entoptic imagery in altered states of consciousness have helped us to better understand the ways in which individuals experience and interpret these images (Rosenshein 2011).

The Study of Entopic Imagery in Altered States

Although entoptic images are a common experience of humankind, they have only become a topic of scientific inquiry within the last few hundred years.   The scientific study of entoptic imagery seems to have begun in 1845, when French psychiatrist Jaques Moreau observed that the structural nature of hallucinations was virtually the same in a wide range of mind-altering conditions.  He found that visual hallucinations reported by individuals suffering from mental illness, as well as those reported by individuals under the influence of entheogens, nitrous oxide, opium, alcohol, and so forth, were very similar in structure (Siegel and West 1975).  Furthermore, in 1888, Dr. Max Simon studied the imagery of schizophrenic hallucinations in patients and discovered a number of repeating motifs of spider webs, ropes, meshes and balls.  These early findings suggested that the structure of visual hallucinations is somewhat consistent across individuals and manners of induction.

Further breakthroughs in the patterns common to entoptic imagery came through the study of mescaline, which was first identified and isolated from the peyote cactus in 1897 by German scientist Arthur Heffter. In 1898, novelist Weir Mitchell published the first modern Western account of the mescaline experience, describing visions of silver stars, gothic architecture, precious stones, and colored fruit (Melechi 2008).

In 1913, A. Knauer and W. Maloney gave mescaline to a number of test subjects and recorded their reported experiences.  One subject described his visions as follows; “immediately before my eyes are a vast number of rings, apparently made of fine steel wire, all constantly rotating” (Knauer and Maloney 1913).  In 1919, mescaline was first synthesised in the laboratory and this accelerated research, revealing a common structure to the visual phenomenon the substance produced; “filigree, cobwebs, cogwheels, flowers, snowflakes – which all appeared to be generated by the eye’s sub-cortical system” (Melechi 2008).

Another scientist who experimented with mescaline on himself recorded the following experience; “If the mescaline taker keeps his eyes closed, he sees riotously colorful ‘mosaics, networks, flowing arabesques, interlaced spirals, wonderful tapestries . . . great butterflies gently moving their wings, fields of glittering jewels . . . soaring architecture . . . and finally human figures and fully formed scenes where coherent histories are enacted’ (Smythies 1953).  These reports on the visions induced by mescaline further exemplify the similar structures found in entoptic images across individuals.  Somehow, the entheogen produces similar images of jewels, interlaced webs and spirals, beautiful architecture and so forth within the visual system.  As we can see from the above reports, different individuals interpret the images they see in slightly different ways, but the similarities and patterns are clearly there.  This research made it very clear that there are patterns in the entoptic images observed by different individuals when consuming mescaline.

Neurologist Heinrich Kluver identified these mescaline patterns and visions as ‘form-constants’, noting the incredible similarities between the images observed by many different individuals.  He noted that hallucinations seem to occur in two stages.  In the first stage, the individual observes four types of geometries; the grid, cobwebs, tunnels or cones, and spirals.  In the second stage, these geometric images are interpreted and elaborated into iconic images drawn from the memory of the observer.

Research into the entoptic images induced by entheogens was continued by Louis Lewin, who spoke of the similarity in imagery that is produced by different types of substances, such as cannabis and mescaline.  He stated that Cannabis produces fireworks and multicolored stars, while mescaline produces colored arabesques, carpets, and filigree latticework (Lewis 1924).  In 1977, Siegel found that individuals exposed to THC and placed in a light and soundproof chamber would see many structurally similar geometric forms which would combine, duplicate, and superimpose with each other. This research once again indicates that, although different entheogens may create somewhat different images, there are definite patterns to be found in entoptic images observed by different individuals and induced by different substances and methods.

Structural Similarities in Entopic Imagery

Through the research into entoptic imagery caused by mental imbalances and entheogens, it became clear that there are certain structural similarities to be found in entoptic imagery as experienced by many different individuals and through many different methods of induction.  These similar structures, or ‘form-constants’, were visually depicted in 1964 in a study by M.J. Horowitz.

Horowitz performed a study on the entoptic imagery in paintings done by schizophrenic individuals, as well as on entoptic imagery as reported by healthy individuals.  He noted that at times, schizophrenic individuals would stop painting and would stare off into space intensely, as if seeing something that no one else could see.  After this, they would paint “simple figures which were different from the previous pictorial forms” (Horowitz 1964, 513).  Patients were asked to draw and describe the visual experiences they were having.  Horowitz found that there were certain images which seemed similar across individuals.  For example, an individual might describe seeing ‘vicious snakes’, and would then make a drawing and redescribe the image as ‘wavy lines’.  ‘Spiders’ might be reduced to circles with radiating lines.  So, although the patients would often describe what they were seeing in different ways depending on the perception of the mind, Horowitz found that most of these images could be reduced to very simple visual constants.  Similar images were found following the ingestion of LSD by healthy subjects.

Healthy individuals were also given a questionnaire to inquire about their experiences of entoptic imagery.  They were asked to draw and describe their visual impressions upon going to sleep and waking up, upon looking at a bright sky or lightly colored wall, upon pressing on the eyeballs with the eyes closed, while intoxicated and so forth.  These are all times when entoptic images are commonly observed.  The subjects reported seeing images very similar to those seen by schizophrenic patients, although they were less likely to describe them as elaborate visions such as snakes or spiders.  These repetitive figure elements were found across schizophrenic individuals, individuals under the influence of entheogens, individuals who were delirious or deprived of sleep, and healthy individuals observing entoptic imagery.  They may be seen below:

Horowitz Form Constants
Horowitz suggested that these images come either from within the eye itself (as in, from floaters and so forth), or from electrical stimulus on the retinal neural networks.  Although these images are usually unseen, under various conditions of enhancement or dis-inhibition of the vision, these images are sent to the processing centers of the brain, where the brain may then interpret them in certain ways depending on the individual.  In some cases, these entoptic images might be interpreted as elaborate imagery and hallucinations – in others, they might simply be seen as simple, un-elaborated figures (Horowitz 1964).

Entopic Imagery in Altered States

So, if entoptic imagery is produced internally in the eye and the brain, how and why are these form-constant structures produced in altered states of consciousness?  According to Neuroscientist Paul Bressloff, geometric visual hallucinations are images of the geometrical structure of the primary visual cortex of the brain in the occipital lobe.  The neurons that make up this area of the cortex are arranged in groups specific to the type of visual stimuli they are sensitive to.  In conditions where the mind enters an altered state, the normal pattern of activity of the visual cortex is destabilized.  The cortex must then discover a new pattern of firing on which it can temporarily settle.  These entoptic ‘form-constants’ are precisely the patterns that constitute a new state of equilibrium.

Other scholars believe that the images one sees when working with entheogens or entering a trance state are a result of heightened awareness.  Entheogens allow the individual to perceive things that are there all the time but that he or she never notices because of distractions coming from mundane physical reality.  Neurons are firing in the visual cortex at all times without stimulation.  These firings are supposedly random, but it is possible that in the trance state the mind becomes capable of recognizing patterns in these firings.  It is possible that these patterns are present at all times, but our usual conditioning prevents us from noticing them in non-trance states.  So, perhaps the form-constants are the patterns in these non-stimulating firings and the trance state allows individuals to recognize them (Rosenshein 2011).

Perhaps our ‘normal’ attention limits our perceptions to a very small range of actual reality.  However, when entheogens or meditative trance states are introduced, it becomes possible for the individual to become aware of these entoptic visual experiences, picking them out of the background ‘noise’ of the visual system.  In other words, it is likely that these entoptic images are always present in the visual system (as with floaters, which are always present but usually only seen when the visual field is filled with a consistent light color, such as when looking at the sky). However, we are not sensitive or open enough to become aware of the patterns present in these images when not in an altered state of consciousness.

Regardless of how they come about, these entoptic images hold great interest for spiritually-oriented researchers and anthropologists.  Although it was only recently that we began to understand the biological reason for these phenomenon, they have likely been viewed as spiritually significant aspects of altered states of consciousness for thousands of years, and may have had a large impact on early human art.  Therefore, researchers are becoming more and more interested in discovering the true meaning behind these images and the ways in which have been interpreted.

Entopic Imagery in Trance Consciousness and Rock Art

From the above information we can see that entoptic imagery does seem to be consistent across individuals and across the conditions through which the images are seen.  In more recent years, many anthropologists have come to believe that these very entoptic images, seen during altered states of consciousness, were the impetus for the creation of both ancient and modern rock art.

In 1988, David Lewis-Williams and Thomas Dowson created a new chart of entoptic phenomenon based on images found in the rock art of the San Bushmen and the Native American Coso, who create their art while in ritual trance states.  Lewis-Williams argues that the form-constants that Kluver found in his mescaline experiments are also found in these trance inspired rock art images.

Lewis-Williams and Dowson compared these images to the images found in Paleolithic art and, based on the similarities between them, hypothesised that the Paleolithic artists were also in shamanic trance states when they produced these images.  He argues that the Bushman, the San, and all currently living human beings share the same neurological structure as the Paleolithic peoples, and that when the brain enters a trance state through dance, chanting,  drumming, the ingestion of entheogens, and so forth, it becomes possible to see entotpic images more clearly.  Indigenous peoples interpreted these images as messages from the spirit world.  Thus, based on this, Lewis-Williams suggested that the Paleolithic artists were in altered states of shamanic trance when they created their images (Lewis-Williams & Dowson 1988).

The similarities between these ancient and modern rock art images and common entoptic phenomena can be seen in the following diagram:

Entoptic Imagery David-Lewis Williams

Form-Constants in Paleolithic Rock Art

When we think of Paleolithic rock art, we often think of dramatic animal imagery, such as that found in the cave of Lascaux.

However, at most sites, the geometric images in Paleolithic rock art outnumber animal and human imagery at a ratio of 2:1 or more (Bahn & Vertut 1997, 166).  Indeed, one can even see these entoptic images in the above painting in the form of the line of black dots that are both below the horse and that make up the lower neck of the horse ! In 2011, Genevieve Von Petzinger mapped out the Geometric Patterns of the Paleolithic world, identifying 26 distinct shapes.  She then looked for patterns of continuity and change over time and space.  She found that at an early age we already see 70% of the patterns being used, and that there is a high degree of repetition of a limited number of shapes, with some being replicated throughout the 20,000 year time span of the study.  This suggests that these symbols were not created at random, but that they were intentional and symbolic. Von Petzinger believes that the abstract nature of these signs is some of the best proof we currently have that these images were not being made purely for their aesthetic qualities, and she suggests that these markings were symbolic attempts to communicate ideas that were not so easy to depict in a physical form.

This theory goes directly in line with the theory of Lewis-Williams and Dowson.  If these images are, in fact, depictions of entoptic imagery seen during trance, and if these images are consistent across individuals and types of trance state, it would make a great deal of sense that we see these images in so many different parts of the world and that they are consistent throughout a very long period of time.  If the trance state and the brain itself does not change significantly across individual and method of trance induction, there would be no reason for the images to do so, either!

It would be nearly impossible at this time to prove beyond a shadow of a doubt whether the Paleolithic peoples were really in altered states when they created their art.  However, according to anthropologist Erika Bourguignon, of 488 societies she surveyed, 437 knew of institutionalized forms of change of consciousness states.  Thus, it seems very likely that most societies that live and have lived on this planet were both aware of entoptic phenomena as observed in altered states of consciousness and gave them cultural and religious significance of some sort (Von Petzinger 2011).

Entoptic Imagery, Shamanism, and Religion

We still see many of these entoptic form-constant images in the abstract patterns of indigenous peoples who work with altered states – the Shipibo art of Peru;

Shipibo Art of Peru

The peyote yarn painting of the Huichol in Mexico;
Huichol Peyote Art
The art of the Tukano shamans in the Amazon, and so forth.

In the shamanic societies of the world, the experience of entoptic imagery is considered to be a valuable tool to catch glimpses of the worlds that lie beyond the material world.  Seeing entoptic visions, and being able to interpret their meanings, is a desired and significant phenomenon.  Indeed, shamans often use tools such as entheogens or sensory deprivation to purposely induce entoptic imagery (Noll 1985)!

According to Lewis-Williams, entoptic imagery is the basis for all trance imagery.  He states that the brain tries to make sense of entoptic phenomena by elaborating it into iconic forms, that is, into familiar objects.  Once the image is ‘recognized’ as being similar to a familiar image, the entoptic images are fleshed out and in this way the shaman is able to enter an altered state of consciousness in which he or she can transform into animals, travel to the lands of the dead, speak to spirits, and so forth.

It seems entirely possible that entoptic imagery may have been the basis for the art of many institutionalized traditions, as well.  For example, we can see traces of entoptic imagery in Buddhist yantras and mandalas;

Buddhist Mandala

in representations of the Egyptian sun god;

Egyptian Sun God
and even in certain representations of the Christian cross (Tausin 2010).

Celtic Cross
Since Western materialism and ‘rationalism’ have become the dominant methods of understanding the human experience, the physical world has become the only valid object of perception and concentration, and anything which goes beyond that, including dreams, visions, and entoptic phenomena, are considered to have no benefit and are sometimes even considered to be signs of mental illness.  However, with advances in neuroscience and an increasing openness in the collective consciousness to the concepts of spiritual, non-substantial phenomenon, we are beginning to come to a point where we can understand entoptic imagery as a phenomenon that is simultaneously biological and spiritual, that may have played a huge role in shaping our experience of life and the cosmos, and that may even be essential to our future development as a spiritual species.

Endless thanks to Keith Cleversley for the original idea for this article!

Special thanks to J. Rosenshein for sharing his wisdom and insight on the topics of the optic system and psychedelic medicines.

 – Keith Edley


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