Nichols’s Primal Eye

Game designer and neural-network modeler Steve Nichols proposes Primal Eye theory, also termed Median Vision Theory (MVT), which holds that phenomenal consciousness, REM dreaming, abstract thought, and self-volitional modeling emerged from the evolutionary atrophy of the ancestral median, parietal, or “primal” eye during the transition from cold- to warm-blooded vertebrate physiology. On Nichols’s account, subjective experience is generated not by the pineal gland itself, nor by a mystical “third eye,” but through the residual functional activity of a lost sensory system: a virtual or “phantom” primal eye reconstructed by the brain from generic action-potential signals. The theory’s central claim is therefore anatomical-evolutionary: when the primal eye disappeared as an external photoreceptive organ, the neural circuitry formerly organized around its direct environmental input was not simply eliminated, but internalized and repurposed for simulation, imagery, dreaming, and the felt unity of conscious experience (Nichols, 1979, 2006, 2025).

Nichols stresses that “third eye” is a misleading expression because the median eye is phylogenetically more ancient than the paired lateral eyes. In extant vertebrates such as the tuatara, the parietal eye remains a light-sensitive structure, although not an image-forming eye in the ordinary visual sense. Earlier experimental and anatomical work on the tuatara and other species showed that the pineal complex participates in photoperiodic regulation, circadian timing, thermoregulation, and related behavioral functions (Dendy, 1899, 1911; Menaker, 1968). Nichols takes this biological background as the starting point for a more ambitious theory of consciousness.

Evolutionary mechanism

Nichols distinguishes three grades of pineal-complex organization.¹ E-2 organisms retain both a functional parietal eye and pineal gland; E-1 organisms retain the gland but have lost the external eye; E-0 organisms possess neither. In the E-2 condition, the organism is comparatively “locked” to external light: behavior is governed by a direct photic channel that coordinates daily and seasonal rhythms, predator-relevant light changes, thermoregulation, and reproductive timing. Nichols characterizes this as a relatively finite-state, hard-wired physiology, in which environmental light functions as a controlling clock or lockstep mechanism.

The decisive transition occurs when the external median eye atrophies. Nichols argues that, as its functions were redistributed partly to the lateral eyes and partly to retained neuronal structures, the brain was released from direct solar control. This loss did not merely subtract a sensory organ; it forced neural systems to become more plastic, self-reconfiguring, and internally generative. The brain, no longer governed by a central external photic input, had to model the world rather than simply respond to it. On this interpretation, abstract thought and self-volition arise in inverse relation to the loss of the primal eye: the less behavior is controlled by direct environmental light, the more the organism must rely on internal simulation, prospective modeling, and centrally evoked representations (Nichols, 2006, 2025).

Nichols introduces an analogy between the evolutionary atrophy of the primal eye with removal of the central "lock-step mechanism" from experimental synchronous digital circuits. In conventional digital design, circuits are governed by a global clock that dictates exactly when signals advance from one stage to the next. This clock forces all logic gates to operate in discrete, synchronized steps (lock-step) to ensure stability and predictability by allowing voltage levels to settle into binary 0s and 1s. By removing the global clock—and deliberately abandoning even the local phase-control handshakes used in standard asynchronous design—Thompson et al allowed the digital logic gates on the FPGA to operate as a completely unconstrained, continuous-time dynamic "ANALOGous to infinite-state" system (Thompson, 1996). Thompson's pivotal discovery was that artificial evolution did not just tolerate these transient dynamics; it actively exploited the rich, physical analog properties of the silicon to solve complex problems (such as tone discrimination and robot control) using a remarkably small number of components. However, Nichols says, the analogy between evolved unconstrained silicon circuits and sans-parietal-eye mammalian/ avian brains is only illustrative, not directly parallel.

Phenomenal consciousness and dreaming

In most species there is no longer any median eye physical circuitry. However, according to Nichols, the vertebrate brain for millions of years grew up alongside primal eye environmentaly originating input, so many deep neuronal structures were in place in our distant ancestors (e.g. Therapsids) since before the warm-blooded interface. Early brains expected data from this sensory input. The phantom effect (or unifying field) arguably is congenitally arising. Closure of the parietal foramen in human infants and evolutionary links between the ancestral E2 state and modern skull development remains a major topic of study (Benoit et. al, 2016; Wu et, al, 2013).

Nichols compares the mechanism to phantom-limb phenomena: when a peripheral organ is lost, the corresponding neural organization may persist and generate experience in the absence of ordinary external input. The “phantom eye” is thus proposed as the biological origin of inner space, visual imagination, daydreaming, and the first-person perspective. In this framework, the self is not an immaterial substance but an evolved phantom-sensory integrator that binds ordinary sensory signals with internally generated simulations. Nichols further argues that this view offers a route into the binding problem, since diverse sensory inputs are translated into a common neural currency of action potentials and integrated through a virtual median-sensory architecture.

Dreaming is central to the theory. Nichols interprets REM as a signature activity of E-1, sans-primal-eye neural organization. When the lateral eyes are closed during sleep and external sensory control is reduced, the unconstrained E1 circuitry is no longer clamped by environmental input and may generate internally driven bursts of activity. Drawing on evolvable-hardware research, especially work on unconstrained circuits and phasic transients, Nichols proposes that REM and dreaming are the subjective expression of such internally released dynamics (Thompson, Harvey, and Husbands, 1996; Thompson, 1998). Dreams are therefore not primarily Freudian wish-fulfilments or Jungian archetypal messages, but episodes of internally generated world-modeling made possible by the loss of the primal eye (Freud, 1900; Jung, 1959; Globus, 1987).

Scope, testability, and assessment

Nichols presents Primal Eye theory as an alternative to both Cartesian pinealism and esoteric third-eye doctrines. Against Descartes, he does not identify the pineal gland as the seat of the soul; against Blavatsky-style mysticism, he argues that vertebrates are not evolving toward a new third eye, but away from an ancient median eye (Descartes, 1637, 1649, 1664; Blavatsky, 1888). In Nichols's view, Descartes was wrong in claiming the pineal gland is intrinsic to sentience since pineal gland removal or calcification does not affect consciousness. Descartes had chosen the pineal gland as integral to consciousness because of its uniquely unpaired and central status in the brain; but he failed to specify how a cellular structure interacts with non-physico-spatial qualia. Leibniz's Law (Identity of Indiscernibles) states that only if two entities share all the exact same properties, they are the same entity (interchangeable). It is because the phantom primal eye is centrally evoked by the cellular as generic APS identically with all the contents of special sense information that Leibniz's "like can only interact with like" condition is satisfied by the non-physical primal eye "monad"—as opposed to Descartes's cellular pineal gland.

The theory makes at least one comparatively clear empirical prediction: species, developmental stages, or individuals retaining more functional parietal-eye tissue should show less of the REM-like internally generative dynamics characteristic of E-1 animals, whereas species with a fully atrophied primal eye should show more robust REM-associated mentation. Nichols therefore proposes comparative work correlating parietal-eye atrophy, pineal-complex organization, neural plasticity, and REM expression across vertebrates.

Primal Eye theory remains highly speculative and is not presently established within mainstream consciousness science. Nichols says that the basic premises (atrophy of primal eye and evolutionary timeline) arise out of evolutionary biology and are not very contentious; however some of his wider inferences can be challenged. Its anatomical and evolutionary premises draw on real features of the pineal complex, but the proposed transition from parietal-eye atrophy to phenomenal consciousness, selfhood, and abstract thought has not been independently demonstrated. Its distinctive contribution is to offer a concrete evolutionary-anatomical hypothesis linking phenomenal consciousness, internal imagery, REM dreaming, neural plasticity, and self-volitional modeling within a single framework.

References

Benoit, J., Abdala, F., Manger, P., & Rubidge, B. (2016). The sixth sense in mammalians forerunners: variability of the parietal foramen and the evolution of the pineal eye in South African Permo-Triassic eutheriodont therapsids. Acta Palaeontologica Polonica.

Blavatsky, H. P. (1888). The Secret Doctrine. London: Theosophical Publishing Company.

Dendy, A. (1899). On the development of the parietal eye and adjacent organs in Sphenodon (Hatteria). Quarterly Journal of Microscopical Science, s2-42(166), 111–153.

Dendy, A. (1911). On the structure, development and morphological interpretation of the pineal organs and adjacent parts of the brain in the tuatara (Sphenodon punctatus). Philosophical Transactions of the Royal Society of London, Series B, 201, 227–331.

Descartes, R. (1637). La Dioptrique. Leiden.

Descartes, R. (1649). Les passions de l’âme. Paris.

Descartes, R. (1664). Traité de l’homme. Paris.

Freud, S. (1900). Die Traumdeutung [The Interpretation of Dreams]. Leipzig & Vienna: Franz Deuticke.

Globus, G. G. (1987). Dream Life, Wake Life: The Human Condition Through Dreams. Albany: State University of New York Press.

Jung, C. G. (1959). The Archetypes and the Collective Unconscious (Collected Works, Vol. 9, Part 1). Princeton: Princeton University Press.

Leibniz, G. W. (1714). La Monadologie.

Menaker, M. (1968). Extraretinal light perception in the sparrow, I: Entrainment of the biological clock. Proceedings of the National Academy of Sciences, 59(2), 414–421.

Nichols, S. (1979). Phantom Eye [BSc (Hons) Philosophy dissertation].

Nichols, S. (2006). The Primal Eye. ISBN 1-87460-308-1.

Nichols, S. (2025). Lost Primal Eye, warm-bloodedness and birth of the self: A new framework for psychology and psychotherapy. Posthuman University Journal, December 2025.

Thompson, A. (1998). Hardware Evolution: Automatic Design of Electronic Circuits in Reconfigurable Hardware by Artificial Evolution. London: Springer.

Thompson, A., Harvey, I., & Husbands, P. (1996). Unconstrained evolution and hard consequences. In E. Sanchez & M. Tomassini (Eds.), Towards Evolvable Hardware (Lecture Notes in Computer Science, Vol. 1062, pp. 136–165). Berlin: Springer.

Wu, X.-J., Xing, S., & Trinkaus, E. (2013). An Enlarged Parietal Foramen in the Late Archaic Xujiayao 11 Neurocranium from Northern China, and Rare Anomalies among Pleistocene Homo. PLoS ONE, 8.