Subjective Visual Phenomena – Johann Purkinje [From Beiträge zur Kenntniss des Sehens in subjectiver Hinsicht, 1819]
The most primal generative visual experiences may be ones created by the visual cortex alone, or ones involving the visual cortex in close collaboration with entheogenic triggers or external psycho-visual simulate, such as stroboscopic lighting. Precursory research material includes Johann Purkinje’s investigations into subjective visual phenomena in Experiments on the Physiology of the Senses and Heinrich Klüver’s later extrapolation of the four groups of entoptic visual phenomena he called Form Constants. The four groups, lattices, cobwebs, tunnels, and spirals, where annotated by Klüver while studying the effects of mescaline.
A recent paper by Tom Froese and others explores the role of Turing instabilities in the generation of spatio-temporal patterns in the disinhibited visual system and its relationship to the prevalence of certain geometric patterns.
‘One of the originally proposed mechanisms for geometric hallucinations is that of a neural Turing mechanism, embodied in the Wilson–Cowan equations  [..] For example, action potential propagation along a neuron’s axon can be directly described by reaction–diffusion equations, and reaction–diffusion equations are analogical to the Wilson–Cowan neural network equations (H. R. Wilson, 1999, pp. 267–268). We can think of the reaction component as the interactions between neuronal cells, and of the diffusion component as the spread of neural activity through local synaptic connections. Similarly, the local structure of neural interconnectivity dictates the type of emergent phenomena that can be produced. Neural network models of geometric hallucinations have gradually incorporated these empirical insights from neural anatomy and physiology, including the spatial arrangement of different neuronal cell types.’
Heinrich Klüver’s Form Constants
The paper goes on to say:
‘A striking feature that differentiates geometric hallucinations from other visual experiences is that they are generated intrinsically when the subject has been decoupled from its environment. The patterns form irrespective of our lifetime learned memories. Indeed, they could be considered internally directed perceptual experiences, since if the proposed models hold true, they are directly formed from the actual biological structure of the visual system. We are said to have a strange subjective experience of looking into oneself, where the patterns we see directly expose the underlying operation of our brains.’
The hyper-chromatic geologies found in the generative work of John Mccabe, who uses Turing instability equations, certainly hints at psychedelic topologies that can be created by these kinds of mathematical exchanges. Its a tidy thesis to suggest that visual representations, of this kind, are isomorphic to the processes involved. When Tim Leary compared psychedelics, in a sense, to the microscope, perhaps it was not entirely metaphorical. If these models are correct the psychotropic vision is a snapshot of the visual cortex looking at itself and looking at its own neural processes – mimicking recursive loops, and algorithms, in order to plot and sketch form constants on its own display.
In The Signs of All Times: Entoptic Phenomena in Upper Palaeolithic Art Lewis-Williams and Dowson explore evidence of motifs and compositions derived from entoptic phenomena in prehistoric art. The earliest humans may have ascribed enough relevance to entoptic visualisations to begin the journey into pictorial representation and subsequently writing.
Previously at Dataisnature: