Entoptic 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.
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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 in to iconic images drawn from the memory of the observer.
Research in to 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.
