Introduction
The target of this comment is a recent and welcome paper (Gamez, 2014) that addresses
foundational issues for neural-correlates-of-consciousness empiricism. This comment
discusses whether Gamez' assumptions actually allow the suggested framework to support
the kind of theory-discrimination necessary for advancing the field. Specifically,
present discussions solely concern the theory-discrimination consequences of assumption
A4, which states that all detailed features of conscious experience are first-person-reportable
(at least, in principle). The present claim is that A4 limits subsequent theory-discrimination
such that Gamez' approach is incapable of addressing certain centrally-significant
controversies in the field. This claim is not meant to demean the value of Gamez'
contribution, but rather to draw attention to still-unresolved issues. The primary
challenges to A4 justified and discussed here are explicit cases in which certain
details of conscious experience are not fully reportable (although these details are
of course experienced by the subject).
Orienting example of a theory-discrimination problem in consciousness research
Consider two alternative theories for spatiotemporal structures (Gamez, p. 2) directly
associated (Gamez, p. 4) with conscious experience (Figures 1A,B). According to theory-I,
activity in a relatively early area, S2 say, is directly associated, whereas according
to theory-II, the direct associate is activity in a later area C1 that e-causally
(Gamez, p. 6) receives information (Shannon, 1948) from S2. By construction of theory-I
and theory-II, area S2 dynamically encodes some information concerning the external
environment that cannot be decoded from C1-dynamics. Put differently, the e-causal
transfer of dynamically-encoded information from S2 to C1 e.g., via S3, loses some
details in granularity of representation. (In Figure 1, granularity is illustratively
depictedas degree-of-spatial-resolution, although in principle it could relate to
any aspect of conscious experience potentially associated with multiple hierarchical
representations in brain-dynamical encoding). Crucially, both theory-I and theory-II
suppose (by construction) that first-person report is limited to information encoded
in C1-activity (because report-governing area R3 is presumed e-causally connected
to S2-encoded information only via C1), so that first-person report definitively cannot
reflect the granularity available e.g., from detailed third-person decoding of S2-activity
using complete knowledge of both S2-dynamics and neural codes. Under Gamez' causality
assumptions, neural-correlates-of-consciousness approaches cannot discriminate between
theory-I and theory-II in order to establish whether it is S2 or C1 that is directly
associated with consciousness, because first-person report and neural dynamics are
identical under the two theories (Figures 1A,B).
Figure 1
Assuming completeness of first-person report can lead to unreliable neural-correlates
conclusions. Pictorial conventions and notation follow Figure 4 in Gamez (2014). (A)
“Theory-I”: conscious experience is directly associated with a relatively early area
S2 that encodes the visual scene at a fine-grained resolution; report is based on
coarse-grained resolution encoded in C1, and does not fully reflect experience. (B)
“Theory-II”: conscious experience is directly associated with the later area C1 that
encodes at a coarse-grained resolution; report is based on coarse-grained resolution
encoded in C1. If completeness of first-person report is assumed, a neural-correlates
approach collecting first-person and brain-dynamical data (identical in A,B) leads
to false certainty that theory-II is correct. (C) “Theory-III”: conscious experience
is associated with both S2 and C1; report is based on C1. For example, S2 might provide
fine perceptual detail to conscious experience, while C1 provides context, contours
etc. (D) Imagination of experience, assuming theory-III is correct: if imagination
evokes activity in C1 but not S2, and C1 provides only coarse-grained detail, then
the imagined experience is not the same as that in the stimulus-driven setting (C)
(absence of S2-participation in conscious experience schematically indicated by graying
of associative arrow). If completeness of first-person report is assumed, a neural-correlates
approach contrasting stimulus-driven and imagined experiences (C,D) will incorrectly
eliminate theory-III in favor of theory-II (B).
Implications for Gamez' framework
The type of theory-discrimination inherent in the theory-I/theory-II example is excluded
by Gamez' assumption A4: theory-I contains aspects of conscious experience not available
even in-principle for first-person report, and therefore lies outside the framework
of Gamez (2014). Thus, the inability of first-person-report-based methodologies to
perform theory-I/theory-II discrimination does not invalidate Gamez' claims that his
framework provides for consistent empiricism. But this inability does draw attention
to limitations not fully emphasized by Gamez, and leads naturally to two questions.
First, are theory-discriminations of the theory-I/theory-II kind relevant to advancing
the field? (If not, then observations here are only of minor interest, although the
relevance of the theory-I/theory-II contrast to past controversies in the field follows
from direct correspondence with the seminal considerations of Crick and Koch, 1995).
Second, if making assumption A4 does establish a significant limitation on Gamez'
framework, are there alternative assumptions providing a logically-consistent basis
for theory-I/theory-II style discriminations whilst preserving rigor and theory-neutrality
(Gamez, 2014)?
Relevance of example-evoked issues to the field
Concerning the first question, one might object that S2-associated theories are implausible,
for example because they are not consistent with empirical data. The primary weakness
of such objections is that they typically appeal to consistency with first-person
report that is precisely at issue in the theory-I/theory-II contrast. For example,
one might claim that first-person-reported properties of conscious experience are
not consistent with known dynamical-encoding regularities pertaining to S2-activity.
But this objection presumes that first-person-report is accurate in full detail, as
is precisely excluded by theory-I. Setting aside empirically-based objections, it
is straightforward to construct further theory-contrasts that create the same challenges
as the example, and are closer to certain central controversies in the field. For
example, consider discrimination between theory-II and another theory-III (Figure
1C), that proposes conscious experience is associated with both S2 and C1. (For example,
C1-activity might be associated with large scale features such as shapes and contours,
and S2-activity might provide a supplementary level of vivid detail). Controversies
of the theory-II/theory-III kind are certainly longstanding, lively and ongoing (Sperling,
1960; Block, 2007; Cohen and Dennett, 2011; Navajas et al., 2014), thus establishing
the relevance of example-evoked issues to the field. Case-by-case demonstration that
every empirical method mentioned by Gamez fails discriminatorily is beyond the present
article's scope, but Figure 1 illustrates problems for Gamez' closest suggestion for
S2/C1-resolution, namely a contrast between stimulus-evoked (Figure 1C) and imagined
(Figure 1D) experiences (Gamez, p. 10). Finally, theory-II/theory-III debates go beyond
the constraints acknowledged in Gamez (2014) (e.g., the exclusion of micro-consciousness
style theories Zeki and Bartels, 1999).
What assumptions extend the reach of theory-discrimination whilst preserving rigor?
Turning to the second question, note that theory-I/theory-II discrimination problems
cannot be avoided by adopting identity-theory (Kim, 1998). For example, even assuming
conscious experience is in some sense metaphysically identical to neural activity,
there is insufficient data (Figures 1A,B) to resolve an S2-identical theory-I from
a C1-identical theory-II.
The present article's scope does not admit full exploration of frameworks that can
both support theory-discriminations of the kind highlighted here and preserve Gamez'
refreshing level of care. To set the stage for future work in this direction, it is
perhaps helpful to contrast approaches of Gamez (2014) and Chalmers (1996). Chalmers
(Ch. 5) raises problems related to phenomenal judgment, and appeals to a pre-experimental
bridging principle based on functionalism (Ch. 6) to exclude S2-style possibilities.
As well as compromising Gamez' theory-neutrality by virtue of the functionalist appeal,
Chalmers' phenomenal-judgment explanation can be directly criticized for its reliance
on non-physical cognition, because this seems to contradict the general tenor of a
causal-closure-of-the-physical setting. Gamez' A4 instead excludes S2-style possibilities
directly, but limitations on theory-discrimination then return us to Chalmers' original
phenomenal-judgment-associated concern: especially under causal closure, what level
of objective, scientific, confidence can be given to subjectively-powerful intuitions
that brain-based report does accurately reflect details of conscious experience?
Conflict of interest statement
The author declares that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.