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Will we ever have a physical science of conscious experience?
John Matthewson
Friday, 17 July 2009 10:09 UTC
If the world were simple we would be able to solve the problem of conscious experience by describing it in physical language and then making hypotheses about how physical events create this conscious experience. We could then poke instruments into brains (or wherever) and check whether the events in the brains were linked to events in experience according to the theory. So all we need is a physical description of conscious experience – its length, breadth, mass, charge, temperature etc….
Of course, obtaining an acceptable physical description of conscious experience appears to be well nigh impossible. There are two main obstacles.
The first obstacle is that the whole enterprise is rejected by those who believe that we cannot know our own experience because there is no time to know it. This problem with the timing of experience is expressed as various types of “regress” argument and by the homunculus paradox – if a person has conscious experience at one instant then this experience could only be known by something looking at that experience in the next instant and so on.
The second obstacle is that it seems impossible to distinguish between the “real world” and “conscious experience”. If a tape measure reads one metre it does so in the real world but also, falsely, appears to measure a metre of experience. A related problem is that it also seems we cannot use instruments to reliably measure our experience itself, say in imagination or lucid dreams, or even use subjective reporting for this purpose without serious doubts.
I am not convinced that these obstacles are insurmountable. It seems to me that two questions need to be answered:
1. Can we ever have a science of conscious experience without a physical description of conscious experience?
2. Is there a fundamental limitation that prevents us from describing conscious experience in a scientific manner?
The nearest that I have seen to an answer to this problem of obtaining an empirical, physical description of consciousness was in an internet paper by Green(2002). The way our conscious experience is extended in time was used to tackle the first obstacle and the second obstacle was tackled by limiting reports of the nature of conscious experience to enumerating the independent directions in which things can be arranged.
Green, A. (2002). A Testable, Geometrical Theory of Consciousness. http://newempiricism.blogspot.com/2009/02/alex-greens-original-paper.html
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Dear John:
I discussed a bit of these ideas with Alex in the Psyche/ASSC extinct discussion lists some years ago.
Of course Relativity is important for a Physicalist view of consciousness, but there are deep problems with the interpretation of mentality in terms of brain geometry. Alex defends (in a very brief summary) that the thalamus is the center of consciousness and that its position in the brain accounts for the geometry of perceived space.
There is another possibility for Physicalist approaches to conscious experiences: Quantum Mind theories, which are far more popular than Relativity-based approaches.
I wonder if he/she is the same Dr. Alex Green who more recently published the paper from which I reproduce the Abstract below.
I am in agreement with your two obstacles, but the second one would benefit from a more precise formulation. Why is it necessary to distinguish the “real world” from “conscious experiences” to achieve a Physicalist explanation of consciousness? In my view, if we are Physicalists (and I am close to be a Non-Reductive one) everything that exists is physical and real (even if we are not able to know, as proposed in R. Almeder epistemological theory of “Blind Realism”), including conscious experiences, spirituality and exotic phenomena as paranormal communication. The idea that conscious experiences are not real is intrinsically Dualist, not Physicalist!Best
Alfredo
Conf Proc IEEE Eng Med Biol Soc. 2008;2008:5724-8.
Identifying rhythms of subthalamic neural oscillations in time-frequency domain.
Wang S, Green A, Stein J, Aziz T, Liu X.
Institute of Sound and Vibration Research, Southampton, UK. s.wang@soton.ac.uk
We aimed to identify neural oscillations in the time-frequency representation of
local field potentials recorded from the subthalamic nucleus. The time-frequency
representation was normalised over the global mean and standard deviation global
normalisation, or against the baseline period at each frequency, local
normalisation. The cross-correlation between beta and gamma oscillations was
enhanced by global normalisation. Furthermore, voluntary movement related
amplitude changes in the gamma band and frequency modulation in the beta band
were revealed by local normalisation. Thus global or local normalisation of
time-frequency representation provides a reliable and effective way to identify
oscillatory rhythms in subthalamic neural activity by reducing noise and
increasing frequency discrimination. It can be used to enhance the detection of
obscure or hidden neural oscillations and improve the sensitivity of post-hoc
analysis. -
Hi Alfredo,
Maybe I didnt put the question clearly: can we ever produce a physical description of conscious experience so that we can make physical theories about it?
In science theories come from observations expressed in physical terms. These physical descriptions can be very simple, for instance, when Newton thought about gravity he used Galileo’s description of two objects falling at the same rate – a physical description – to propose that the force of gravity is proportional to mass (see note below). The moral of this story is that you cant have a physical theory without a physical description of the object of the theory.
What I am asking is whether any physical description of conscious experience is possible. Your answer seemed to be that quantum physics could be used as an “approach” but you cant do science without knowing what your approach is approaching. What is the physical description of this “conscious experience” that a qm theory might approach? Gravity explains physical observations such as why we stay on the ground and why two balls fall at the same rate – what physical observations would qm theories of mind explain?
In fact qm theories of mind contain an assumption that conscious experience is a set of events in spacetime. These theories are about how observables originate in quantum theory so they need physical descriptions involving length, breadth and depth to obtain the position of an event as an observable. They also need a description of time in experience if motions are to be analysed. On reflection it seems that your mention of your support for qm theories suggests that you agree with the characterization of conscious experience as events in spacetime (observables).
Another implication of qm theories is that the predicted observables would be localised even though they might originate in a delocalised qm field. Where are these classical events (observables) and how would their physical layout in the brain map to their positions in the spacetime of conscious experience?
Note: Newton reasoned as follows: take two masses, m and M, then f = mg and F=Mg, so g being constant for both masses means force is proportional to mass. Therefore just seeing two balls falling at the same rate gave Newton a big insight into gravity.
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I don’t think we can have a physical science of conscious experience until we agree on a bridging law that relates empirical data to instances of phenomenal content. Accordingly, I have proposed what I think is such a law in the domain of human consciousness:
First law of conscious experience: For any instance of conscious experience there is a corresponding analog in the biophysical state of the brain.
I prefer to speak of a biophysical science of conscious experience rather than a physical science because this manner of reference constrains consciousness to biological entities. This conforms to the fact that we have no evidence of consciousness ( C ) in non-biological structures while we have abundant evidence of C in the human organism, and somewhat less compelling evidence of C in other animals.
If we accept the First Law, developing a biophysical science of consciousness will require the theoretical specification of biophysical mechanisms that can generate brain analogs corresponding to measured/reported properties of specific instances of phenomenal content.
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Hi Arnold,
Can we firm up on your law: “For any instance of conscious experience there is a corresponding analog in the biophysical state of the brain.”?
Are you proposing a one to one correspondence between some physical event in the brain and an event in conscious experience? (In Alfredo’s qm theory this would be a correspondence between an observable and and an event in experience).
Would you consider that the adjacency relationships of correlated brain/experience events are preserved? For instance that the brain activity that corresponds to “!1” in experience has the analogs of “!” and “1” adjacent to each other somewhere in the space occupied by the brain.
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John,
This is the kind of close analysis that is needed.
You wrote:
“Would you consider that the adjacency relationships of correlated brain/experience events are preserved? For instance that the brain activity that corresponds to “!1” in experience has the analogs of “!” and “1” adjacent to each other somewhere in the space occupied by the brain.”
In my theoretical model, the adjacency relationship for ! and 1 in “! 1” would necessarily exist in the functional spatiotopic neuronal structure of retinoid space, but not necessarily in the geometric space of the brain. In other words, the brain’s spatiotopic representation of “!1” is a proper analog of the phenomenally experienced pattern. Is the distinction between topology and geometry clear?
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Hi Arnold,
You wrote: “Is the distinction between topology and geometry clear?”.
The topological mapping of sensory input produces an electrical ‘image’ that is like the reflection from a seriously bent fairground mirror. A fairground mirror largely preserves the adjacency relations between parts of the optical object but does not preserve length or angular relations or plane topology in the optical image. If your ‘retinoid system’ is like other recipients of sensory input it would also preserve relations of what is adjacent to what.
Before considering the distorted sensory topological maps in more depth it would be useful to examine the various mappings between sensation and experience. There are several mappings at work in generating our experience. The first is from the retina to the brain, the second is from the brain to experience and the third is the overall mapping from the world to experience. The overall mapping allows us to see the symmetry of circles and the straightness of lines.
If our experience were instantaneous it would not matter if it was really like the image from a distorting mirror – all our functional responses would be OK. We could report an experience containing a circle as circular even if there were truly an ellipse in our experience because the report would use data from the actual object in the world beyond our body. The only problem is that experience cannot exist for a true instant, for no time at all.
If our experience is extended in time, if the ‘specious present’ exists, then distorted mappings will be highly problematical. A rotating ellipse is not at all like a rotating circle.
It is intriguing that the brain goes to great lengths to preserve the mapping from the world to experience. If the correspondence between the world and experience is disturbed by wearing distorting prisms in front of the eyes then the visual system adapts to restore the view over a few days or weeks (Tanaka et al 2007). So the visual system adapts to provide an apparently faithful geometrical mapping in experience even though the topological mapping in the cerebellum, cortex etc. does NOT appear to be faithfully geometrical. How does it do the last part of this adaptation, the seeing of a rotating circle as a circle with all the symmetries that this implies?
In contrast to the known sensory topological mapping, a faithful geometrical mapping of sensory input would involve the preservation of the lengths and separations of events on the retina as well as the replicating of its slightly curved surface topology. Unfortunately the cortex, cerebellum etc do not seem to contain faithful geometrical mappings. However, it would be easy for the brain to reconstruct a faithful geometrical mapping of sensory input from the data about what is next to what (the adjacency data) because each point of activity in the LGN, SCN, cortex etc. corresponds to a small, geometrical zone of retinal activity (see Note below).
Another alternative to actually producing a faithful geometrical map would be if the distance between the nodes of a normal sensory topological map were reduced to zero by some effect such as qm entanglement or the existence of a geometrical phenomenon that accomplished this. Provided each node represented an equal area of retina putting all the nodes ‘shoulder to shoulder’ would restore the geometrical form. I prefer this option to the reconstruction of a faithful geometrical map.
Tanaka, Y, Miyauchi, S., Misaki, M., Tashiro, T. (2007). Mirror symmetrical transfer of perceptual learning by prism adaptation. Vision Research Volume 47, Issue 10, May 2007, Pages 1350-1361
Note: Adjacency data is sufficient to reconstruct a plane image, for example, if you cut up a photo into a vast number of small squares of equal size and mark each side of each square with the identity of the square that abuts it then it is easy to reconstruct the photo by simply placing the squares on a surface in the appropriate positions with equal separations between the squares.
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John,
You wrote:“There are several mappings at work in generating our experience. The first is from the retina to the brain, the second is from the brain to experience and the third is the overall mapping from the world to experience.”
When you say that there is a mapping from brain to experience, are you suggesting that conscious experience is not constituted by the biophysical activity of the brain?
JM:“So the visual system adapts to provide an apparently faithful geometrical mapping in experience even though the topological mapping in the cerebellum, cortex etc. does NOT appear to be faithfully geometrical. How does it do the last part of this adaptation, the seeing of a rotating circle as a circle with all the symmetries that this implies?"
This is accomplished (roughly) by the size-constancy mechanism in the retinoid system. As a circle is rotated on its vertical axis, the retinal image of the circle is transformed in retinoid space to roughly compensate for the change in its geometric projection. You can get an idea of how this works by forming an after-image of a disc and then fixating a blank planar surface that you rotate on its vertical axis. The afterimage will become an ellipse that defines the compensatory adjustment in the retinoid system for approximate conservation of the symmetry of a rotating circle.
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John,
You wrote: “Another alternative to actually producing a faithful geometrical map would be if the distance between the nodes of a normal sensory topological map were reduced to zero by some effect such as qm entanglement or the existence of a geometrical phenomenon that accomplished this. Provided each node represented an equal area of retina putting all the nodes ‘shoulder to shoulder’ would restore the geometrical form. I prefer this option to the reconstruction of a faithful geometrical map.”
In the retinoid Z-planes, each autaptic cell (retinotopic and spatiotopic node) represents an equal area of the retina. The actual geometric brain space between these principal autaptic neurons represents nothing. So these autaptic cell nodes are phenomenally ‘shoulder to shoulder’.
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Arnold,
This need for a “mapping from brain to experience” is the cause of dualism! You are right to pull me up short on it and request that I explain myself. I will explain why I believe in a “mapping from brain to experience” yet do not think that dualism is necessary.
The essence of this thread is that if we can describe conscious experience in a scientific way we will be able to create hypotheses about its physical/biophysical nature. I agree with Green that we can indeed produce a physical description and I have elaborated this description in Time and Conscious Experience . The essential point of both of these descriptions is that conscious experience is arranged in more than three dimensions. We can hear whole words and bars of tunes and see movement so our experience is also arranged in dimensional time.
This physical description is not congruent with the three dimensional form of your retinoid system or any other 3D slice of the brain. This lack of congruence occurs because our experience is arranged in at least four dimensions so there will be a need to map the three dimensional forms that are measured in the brain to the multidimensional form of experience. This mapping is not trivial because dimensional time interacts with the spatial dimensions in an unsusual way. The spatial dimensions interact according to Pythagoras’ theorem (dr^2 = dx^2 + dy^2 + dz^2) but when dimensional time is introduced a negative sign appears in the metric (ds^2 = dx^2 + dy^2 + dz^2 – (cdt)^2). As a result we cannot just stack up three dimensional sections of brain to get the four dimensional part of the form of experience but rather we must conceive of the 3D sections losing all separation at a 4D point. (See Some notes on projective geometry ).
In fact this idea of the relationship between the 3D forms in the brain and conscious experience is no more than the current standard model of physics. The reason that people slip into dualism is that they do not apply the standard model, they invent their own space-time in which time is represented by a simple succession of 3D forms like frames in a film (See Materialists should read this first ). This false space-time does not allow the 3D forms in the brain to create experience so people who refuse to accept the standard model of physics either end up being eliminativists or dualists.
Your afterimage example is fascinating. It seems to suggest that a purely neural phenomenon (the afterimage) is actively rearranged to be consistent with a sensory phenomenon. I have not seen your example in action, perhaps I should stare into the top of a spiral energy saving light bulb and see how the afterimage is affected by a rotating piece of card – would this replicate your experiment?
You wrote: “In the retinoid Z-planes, each autaptic cell (retinotopic and spatiotopic node) represents an equal area of the retina. The actual geometric brain space between these principal autaptic neurons represents nothing. So these autaptic cell nodes are phenomenally ‘shoulder to shoulder’.”
I would consider that in 3D the spaces exist, they would represent nothing in a computational model but experience is not computational. From the reasoning given above the spaces would only disappear as they are mapped onto a 4D form.
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John,
You wrote: “This physical description is not congruent with the three dimensional form of your retinoid system or any other 3D slice of the brain. This lack of congruence occurs because our experience is arranged in at least four dimensions so there will be a need to map the three dimensional forms that are measured in the brain to the multidimensional form of experience.”
The autaptic neurons in the Z-planes of the retinoid system have short-term memory and are assumed to compose a 4D phenomenal space. It is described as a 3D neuronal structure as a matter of convenience (like any other circuit diagram). But since it has dynamics as well as structure, it must be understood as a biophysical mechanism operating in time as well as space (of course, no structure can exist in zero time). The issue of time, especially phenomenal time is tricky. Einstein’s space-time is an abstract formalism that has proven useful in our understanding of the universe. But we must acknowledge that this scientific formalism, like all abstractions, useful or not, is a product of human biology. From a phenomenological perspective our conscious experience of time is difficult to pin down. But in the 4D manifold of the retinoid world, nothing happens instantaneously. Because of the short-term memory properties of the retinoid system, our experiential tour through retinoid space always fuses a representation of what is happening now (strong), before (weaker), and an anticipation of next (weakest). As we attend to various regions of the phenomenal space around us, our heuristic self-locus travels a path through the space-time plenum of the retinoid structure. The formal description of all of this is not a part of the mechanism that generates the description.
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