A serious crisis is identified in theories of neurocomputation, marked by a persistent disparity between the phenomenological or experiential account of visual perception and the neurophysiological level of description of the visual system. In particular, conventional concepts of neural processing offer no explanation for the holistic global aspects of perception identified by Gestalt theory. The problem is paradigmatic and can be traced to contemporary concepts of the functional role of the neural cell, known as the Neuron Doctrine. In the absence of an alternative neurophysiologically plausible model, I propose a perceptual modeling approach, to model the percept as experienced subjectively, rather than modeling the objective neurophysiological state of the visual system that supposedly subserves that experience. A Gestalt Bubble model is presented to demonstrate how the elusive Gestalt principles of emergence, reification, and invariance can be expressed in a quantitative model of the subjective experience of visual consciousness. That model in turn reveals a unique computational strategy underlying visual processing, which is unlike any algorithm devised by man, and certainly unlike the atomistic feed-forward model of neurocomputation offered by the Neuron Doctrine paradigm. The perceptual modeling approach reveals the primary function of perception as that of generating a fully spatial virtual-reality replica of the external world in an internal representation. The common objections to this “picture-in-the-head” concept of perceptual representation are shown to be ill founded.

It is tough to relate visual perception or other achievements to physiological processing in the central nervous system. The diagrammatic, algebraic, and verbal pictures of how sights seem to Lehar do not advance understanding of how we manage to see what is in the world. There are well-known conceptual reasons why no such purely introspective approach can be productive.

Lehar's Gestalt Bubble model introduces a computational approach to holistic aspects of three-dimensional scene perception. The model as such has merit because it manages to translate certain Gestalt principles of perceptual organization into formal codes or algorithms. The mistake made in this target article is to present the model within the theoretical framework of the question of consciousness. As a scientific approach to the problem of consciousness, the Gestalt Bubble fails for several reasons. This commentary addresses three of these: (1) the terminology surrounding the concept of consciousness is not rigorously defined; (2) it is not made evident that three-dimensional scene perception requires consciousness at all; and (3) it is not clearly explained by which mechanism(s) the “picture-in-the-head,” supposedly represented in the brain, would be made available to different levels of awareness or consciousness.

Lehar misrepresents the Neuron Doctrine and indirect realism. His conclusions on consciousness are unjustified. The Bubble Gestalt perceptual modeling disconnected from neuroscience has no explanatory power.

This new heuristic model of perceptual analysis raises interesting issues but in the end falls short. Its arguments are more in the Cartesian than Gestalt tradition. Much of the argument is based on setting up theoretical straw men and ignores well known perceptual and brain science. Arguments are reviewed in light of known physiology and traditional Gestalt theory.

Lehar's lively discussion builds on a critique of neural models of vision that is incorrect in its general and specific claims. He espouses a Gestalt perceptual approach rather than one consistent with the “objective neurophysiological state of the visual system” (target article, Abstract). Contemporary vision models realize his perceptual goals and also quantitatively explain neurophysiological and anatomical data.

Aspects of an example of simulated shared subjectivity can be used both to support Steven Lehar's remarks on embodied percipients and to triangulate in a novel way the so-called “hard problem” of consciousness which Lehar wishes to “sidestep,” but which, given his other contentions regarding emergent holism, raises questions about whether he has been able or willing to do so.

Lehar's revival of phenomenology and his all-encompassing Gestalt Bubble model are ambitious and stimulating. I offer an illustrated caution about phenomenology, a more fractured alternative to his Bubble model, and two lines of phenomena that may disqualify his isomorphism. I think a perceptual-inquiry model can contend.

Vision scientists standardly assume that the goal of vision is to recover properties of the external world. Lehar's “miniature, virtual-reality replica of the external world inside our head” (target article, sect. 10) is an example of this assumption. I propose instead, on evolutionary grounds, that the goal of vision is simply to provide a useful user interface to the external world.

“Psychological relativity” means that “an observation is a relationship between the observer and the event observed.” It implies a profound distinction between “the internal first-person as opposed to the external third-person perspective.” That distinction, followed through, turns Lehar's discourse inside-out. This commentary elaborates the notion of “psychological relativity,” shows that whereas there is already a natural science of perceptual report, there cannot also be a science of perception per se, and draws out some implications for our understanding of phenomenal consciousness.

The “Gestalt Bubble” model of Lehar is not supported by the evidence offered. The author invalidly concludes that spatial properties in experience entail an explicit volumetric spatial representation in the brain. The article also exaggerates the extent to which phenomenology reveals a completely three-dimensional scene in perception.

Lehar tries to build a computational theory that succeeds in offering the same computational model for both phenomenal experience and visual processing. However, the vision that Lehar has about isomorphism in Gestalttheorie as representational, is not adequate. The main limit of Lehar's model derives from this misunderstanding of the relation between phenomenal and physiological levels.

The electrophysiological perspective presents an electrical field that is continuous throughout the body, with an intense focus of dynamically structured patterns at the cephalic end. That there is indeed an isomorphic mapping between the detailed holistic patterns in this field and in perception (at some level) seems certain. Temporal binding, however, may be a greater challenge than spatial binding.

The Gestalt Bubble model describes a subjective phenomenal experience (what is seen) without taking into account the extraphenomenal constraints of perceptual experience (why it is seen as it is). If it intends to be an explanatory model, then it has to include either stimulus or neural constraints, or both.

Lehar proposes an interesting theory of visual perception based on an explicit three-dimensional representation of the world existing in the observer's head. However, if we apply Occam's razor to this proposal, it is possible to contemplate far simpler representations of the world. Such representations have the advantage that they agree with findings in modern neuroscience.

Certain features of perception – the quale red, for example, and other qualia – must be regarded as additions to the materialist neurophysiological picture of perception. The perception of three-dimensional volumetric objects can also be seen as qualitative additions to the neurophysiological processes in the brain, possibly without additions to the information content.

The Gestalt Bubble model of visual consciousness is a courageous attempt to take the first-person perspective as primary in the study of consciousness. I have developed similar ideas as the Virtual Reality Metaphor of consciousness (Revonsuo 1995; 2000). I can, hence, only agree with Lehar about the general shape of a proper research strategy for the study of consciousness. As to the metaphysical basis of the research program, I have, however, several reservations about panexperientialism.

Lehar (rightly) insists on the volumetric character of our experience of space. He claims that three-dimensional space stems from the functional three-dimensional topology of the brain. But his “Gestalt Bubble” model of volumetric space bears an intrinsically static structure – a kind of theater, or “diorama,” bound to the visual modality. We call attention to the ambivalence of Gestalt legacy and question the status and precise import of Lehar's model and the phenomenology that motivates it.

Lehar argues that a simple Neuron Doctrine cannot explain perceptual phenomena such as size constancy but he fails to discuss existing, more complex neurological models. Size models that rely purely on scaling for distance are sparse, but several models are also concerned with other aspects of size perception such as geometrical illusions, relative size, adaptation, perceptual learning, and size discrimination.

Collapsing three-dimensional space into two violates Lehar's “volumetric mapping” constraint and can cause the visual system to construct illusory transparent regions to replace voxels that would have contained illumination. This may underlie why color constancy is worse in two dimensions, and argues for Lehar to revise his phenomenal spatial model by putting “potential illumination” in empty space.