referee #1 anon
this ms is now greatly improved. the author now addresses several of the most problematic aspects implied by his model, and he also has been able to connect it much better with the previous literature that advances related views. however, a few weaknesses still remain. they should be dealt with, at least briefly, before the paper is accepted for publication.
1. theories of neural synchronization.
in the introduction, the author claims that theories of synchronous oscillations are not yet specified sufficiently to know exactly how they address the issue of perceptual representation. i think this ignores recent advances in the field that should be discussed. for example, roelfsema & singer (1998, cerebral cortex 8: 385-396) present a detailed model of the gestalt phenomenon of connectedness in defining coherent objects, and propose neural synchronization as the mechanism behind this phenomenon. it seems that the mechanism they propose produces neural representations isomorphic with the objects subjectively perceived. furthermore, singer's group (e.g. engel et al 1999; consciousness and cognition 8: 128-151) hypothesize that coherency of neural activity may be the gateway to consciousness. how do these models and ideas relate to the gestalt bubble model?
the author's treatment of spatial hemineglect remains too superficial and includes no references to the most recent original literature on this matter. he does not mention, although he should, that one of the traditional explanations of neglect in the literature is that "conscious representations of contralesional space may be more or less completely lost" (vallar 1998, trends in cognitive sciences 3, p. 87). that idea would seem to be identical to the one offered by the author. however, in recent years it has been noted that the disorder's manifestations are very complex and that "it fractionates to a number of discrete patterns of impairment" (vallar p. 88). in fact, lehar's suggestion that hemineglect could be explained by "damage to a left half of a three-dimensional imaging system *used both for perception and the generation of mental imagery*" has already been contradicted by the evidence. there are cases of *dissociation* between hemineglect in mental imagery and visual perception (e.g. coslett 1997, brain 120: 1163-1171; beschin et al. 1997, cortex 33: 3-26). therefore, it would seem that perception and imagery do not depend on one single spatial representation. how can the bubble model handle this complication?
furthermore, there are peculiar dissociations as to what the neglect patient can and what he cannot perceive; for example many patients can describe the global gestalt of a figure, but when copying its local features, leave those on the left side out (marshall & halligan 1995, nature 373: 521-523). present accounts of the multiple forms of neglect refer to several spatial maps and their interaction (e.g. ladavas et al. 1997, experimental brain research 116: 493-500). to make the bubble model truly relevant for the description and interpretation of hemineglect, it should be explicitly connected with these latest findings and models of the phenomenon, rather than a textbook-level general description. otherwise it remains unclear whether the bubble model adds anything to traditional descriptions and explanations of neglect.
3. visual phenomenology outside the focus of attention or eye fixation
it is unclear whether the model describes truthfully all of our visual phenomenology. for example, before we focally attend to an object, and after attention has departed, there are only "preattentive object files" or "shapeless bundles of basic visual features" (e.g. wolfe & bennett 1997, vision research 37, 25-43). can the model account for this fuzzy phenomenology outside the focus of attention? also, outside the plane of depth where we currently fixate, we have double vision: when we fixate far, near objects appear in two and vica versa. what happens outside the plane of depth of fixation according to the bubble model? or does the model only account for visual phenomenology within the focus of attention? in that case it is not a model of the whole phenomenal visual field.
4. the ontological status of consciousness in the bubble model
the author makes it very clear that the bubble model is *epistemologically* committed to indirect realism. however, it remains unclear what the *ontology* of consciousness is according to the model. the author refers to psychophysical parallelism and explicates his view in terms of a computer metaphor of how patterns of voltages inside the computer can represent meaningful information. he says that phenomenal experience is "a data structure", "pattern of energy in the physical brain", "pattern of activation", and that "we observe the the information" (not the physical medium itself). these characterizations suggest that the author endorses standard philosophical functionalism and representationalism about consciousness, as formulated and defended e.g. by tye (1995, ten problems of consciousness, mit). lehar certainly seems to say that we observe the *content* of information (or representation), not its physical *vehicle* in the brain. the problem is that representationalists who build their theory on exactly that basis (e.g. tye, dretske), claim that phenomenal content is identical to representational or *intentional* content, and since intentional content is not in the brain, also phenomenology is not in the brain! thus, they are *externalists* as to the content of consciousness. by contrast, lehar seems to deny externalism, but at the same time he seems to accept the distinction between the physical medium of information, and its content, and he says that his theory only concerns the latter. lehar should clarify to what extent he accepts standard representationalism (as defended by e.g. tye, 1995), because now he seems to accept some of its ideas while denying others, which makes it rather difficult to figure out what the metaphysical commitments of his theory are, or whether they even can be coherently formulated.