Oxford University Press (2004)
This book is worth reading for a number of interesting areas of discussion. It attempts to use aspects of synaesthesia to refute the still dominant functionalist theory of consciousness. It argues that intentionality or meaning arises from unconscious processing, and also that there is no true representation of the external world in the brain. Because of these last two points, it is argued that much of the philosophical baggage of consciousness studies can be left behind, and discussion of consciousness should be focused purely on qualia. Gray does not think we yet have an explanation for qualia. He takes the possibility of quantum consciousness, at least in the Penrose form more seriously than most mainstream investigators, although he argues that it contains no explanation for the selection of particular qualia. He sees conscious as being selected for by evolution, because it is causal, but causal in a sense that does not involve agency or freewill. Unconscious systems are claimed to respond to conscious perception, but only in the sense that our brains can respond to a sketch as a reminder, with the sketch having no agency of its own. This part of the discussion seems rather incomplete. Gray has relatively little to say about cognitive processing, the conscious emotional aspects of the brain, or the relationship between these two, which is known to be crucial in determining preferences for action and behaviour.
Gray stresses that conscious experience has no scientifically understood links with neuroscience or behavioural science. Without such links, there can be no understanding of the interaction of consciousness with the physical world. Neuroscience has built up a detailed knowledge of neurons, but this is viewed here as having made no contribution at all to explaining consciousness. Most neuroscience experimentation has not been aimed at understanding consciousness, but at understanding the movement of energy in the brain. Biology as such makes do with two systems, firstly the laws of physics and chemistry, and secondly feedback mechanisms that respond to a variable, which is being controlled. In fact, neuroscience has created a complete outline of brain processing without involving consciousness. There is nothing for consciousness to do within conventional neuroscience, and the existence of consciousness is something of an embarrassment to the theory. But Gray argues that while experimentation has shown much of what we perceive to be an illusion, we should hold onto the fact of conscious experience, for without conscious experience, it would be impossible to have an illusion in the first place. The unconscious mind is argued not to be capable of having an illusion, but only of making an error. In contrasts to an error, an illusion continues even when it is known to be an illusion. Thus knowing that a film is a series of frames does not prevent us from seeing it as continuous.
Refuting functionalism: Gray goes on to discuss functionalism, which he views as the dominant form of consciousness theory. According to functionalism, consciousness is the nature of certain complex systems, regardless of whether they are is made of neurons, silicon chips or some other material. The underlying tissues or machinery is irrelevant. Further to that, consciousness relates only to functions performed by the brain or other system, and does not arise as a result of anything that is non-functional. In looking at the qualia red and green, functionalism says that all that exists are responses, by which the individual’s behaviour demonstrates the capacity to discriminate between red and green. For any discriminated difference in qualia, there must be a difference in function. It is also claimed that for every discriminated difference in function, there is a difference in qualia.
Gray claims to refute functionalism, on the basis of data from research into synaesthesia performed at the Institute of Psychiatry in London. In discussing this question further, Gray looks at synaesthesia, where modalities become mixed, as when numbers or sounds are experienced with colour. Extensive experimentation in recent years has demonstrated that synaesthesia is a real and observable brain state, and is most likely the consequence of abnormal projections into the V4 colour region of the visual cortex from other parts of the brain. Brain scanning studies showed that when words were spoken, in addition to the normal activity in the auditory cortex, the V4 colour vision area in the visual cortex became active, in a way which did not occur in normal subjects. There was no related activation in V1 or V2, the earlier stages of the visual pathway. The conclusion drawn from a whole series of experimentation was that the ‘word-colour’ type of synaesthete has an abnormal projection from the auditory cortex into the visual cortex causing the V4 colour area to produce consciousness of colour. However, there is no evidence that this colour sensation has any function. Thus, there is no relationship between the occurrence of the synaesthete’s colour experiences and the linguistic function that triggers them. Gray argues that this phenomena refutes the functionalist theory’s analysis of conscious experience.
Intentionality and the unconscious brain: Gray argues that a large proportion of the brain’s activity is unconscious. Consciousness is commonly estimated to lag about 250 milliseconds behind an event being registered by the sense organs, but much action and behaviour takes place more rapidly than this. He also discusses the existence of separate systems for conscious and unconscious processing. This is the case in the visual system, where there is a ventral stream that underlies conscious perception, and a dorsal stream that underlies rapid but unconscious actions.
Conscious experience or more specifically the contents of consciousness are usually about something, and this is described as ‘intentionality’, whereas movements of energy in the brain are just themselves, and are not about anything. Intentionality is another aspect of the ‘binding problem’, as to how the different modalities, such as sight and hearing, are bound together into a single conscious experience. Gray points out that without binding, eating a banana could involve seeing yellow, feeling a surface and tasting something without the unifying awareness of a particular object known as a banana. Intentionality can also be referred to as meaning, the meaning of the yellow colour etc. is a banana. Without this binding, things would be just meaningless shapes, edges, colours etc. Consciousness appears to arise where modalities come together. This also involves the idea of categories that usually bridge two or more modalities, as with the example of the banana, as a particular category of object.
Gray sees the unconscious brain as containing subsystems that can be regarded as what he calls servomechanisms dedicated to controlling a particular variable, such as the distance between a hand and an object that is going to be grasped. These servomechanisms are often linked to actions. In contrast, conscious perception can be just about perception, such as looking at a sunset.
Despite this distinction, Gray argues that intentionality is based on unconscious processing. The processing in the visual cortex that underlies conscious perception is not itself conscious. Instead, the perception springs into consciousness fully-formed, including the intentionality of what the perception is, or is about. To prove this point, Gray use the example of pictures that can be either of two things, such a duck or a rabbit. They are never hybrid, but are always completely duck or completely rabbit. The perception of a duck or rabbit is argued to be constructed unconsciously up to the last moment. The actual process of binding, as in the binding problem, is also suggested to be an unconscious result of synchronous firing within and between brain regions. Gray’s conclusion from this part of his discussion is that intentionality arises from the physical and chemical structure of the brain, but also that if intentionality can be constructed out of unconscious processing, it is unlikely to produce a solution to the ‘hard problem’ of how consciousness arises.
Representation: Gray goes on to discuss the question of the representation of the external world in the brain. First of all, he reminds us that the external world is nothing like what it appears like in conscious perception. The external world is bits of energy fluctuating in the vacuum, with none of the qualities of solidity, colour etc. attributed to the perceived world. But the author goes further than this. He dismisses what he calls the fall back position, which is to think that the perception of something, a cow for example, is a representation, in the sense of resembling the cow as it really exists. Gray argues that our only direct knowledge of the cow is a brain state. We have has no direct knowledge of the cow as it really is, and it is therefore meaningless to argue that the cow brain-state is a representation of the real cow.
Gray argues the conscious perceptions should be treated as signals. Signals have no need to resemble the thing about which they communicate. A whistle might warn thieves of the approach of a policeman, but a whistle is nothing like a policeman. Perceptual experiences are seen as signals, about what observers might expect about their environment. However, he stresses that these perceptual signals arise in the brain, and do not have any kind of external existence. This is not to say that we cannot deduce useful information about the real world from perception. Thus for example visual perception is a good guide to the reflectance of surfaces, which in turn often has survival value for an organism. Thus there is a ‘fit’ between the external world and the model constructed in the brain, otherwise we would not have much success in interacting with the world.
Gray also emphasises that conscious perception is not voluntary. Perceptions just pop into consciousness, and are argued here to come from unconscious processing. Furthermore, it is claimed that only a tiny proportion of the data that could potentially enter consciousness actually does. It is possible to distinguish between two types of unconscious processing. Firstly, processing that can never come into consciousness, and secondly processing which is potentially conscious but remains unconscious.
Philosophical Baggage: Gray’s message is that we can dispense with much of the philosophical baggage of modern consciousness studies, as regards intentionality and representation, because these are either unconscious or non-existent. Given the reams that have been written on these subjects, and the meagre gains in our understanding of consciousness, many might be glad to dispense with this baggage train. Instead, Gray says we should concentrate on the qualia of subjective conscious experience, as the only aspect of the brain that involves consciousness.
Function of consciousness as comparator and late detector: Gray views the function of consciousness as a ‘late error detector’. The brain is argued to be a ‘comparator’ system that predicts what should happen and detects departures from that prediction. It is suggested that consciousness is particularly concerned with novelty or error. It is also viewed as something that causes us to review past actions, and to learn from errors in these actions. Late error detection permits more successful adaption, if a similar situation emerges in the future. Gray looks at the question of pain. We remove our hands from a hot surface before consciously feeling the pain of touching it. The pain involves is argued to be a rehearsal of the action that led to it, and has the survival advantage of making a repetition of the damaging action less likely.
Gray accepts that there are many unconscious systems that detect errors, so this on its own does not produce a survival value for consciousness. However, he distinguishes consciousness as being multi-modal, and as directing us towards whatever is most novel within several modalities. The brain takes account of plans as to what to do next, plus memories of past regularities, in assessing what is likely to be the next stage of a particular process. These predictions are submitted to a comparator, but still at an unconscious stage. Only the unexpected outcomes, or feedback for the continuation of motor action enters consciousness. We are only conscious of things that change unexpectedly, or things that are particularly important at the moment.
Gray views the function of consciousness as the construction of relatively constant perceptions from ever-changing sensory inputs. The trick is the transmutation of the ever-changing into the constant. The survival value of consciousness is seen as the ability to take a second look, where actions or predictions have gone wrong. The actual detection of departure from prediction is argued to be at the unconscious level, and the perception of error then just jumps into consciousness.
The perceptual system is said to construct a relatively stable picture of the external world, against which unconscious processing by the comparator reports expectations, error and change. Experimental data suggests this is useful with navigation. A route once learnt can be re-used without trial and error on the basis of a few major land marks. Similarly in other circumstances such as physical actions, consciousness can act by providing information on key variables, which feed back into action.
Gray goes on to make the distinction between egocentric and allocentric views of the spatial world. The egocentric is concerned with action, and is centred on parts of the body. Conscious perception, however, uses an allocentric system where the relationship between objects is independent of the conscious observer. Damage to the inferior parietal lobule, as in Balint’s syndrome, leads to errors in binding together the different features of a single object. This is related to the parietal’s involvement with spatial perception, and is taken to suggest that binding requires that objects are attributed to a particular spatial location. Egocentric space is suggested to be unconscious in the parietal lobule, with a projection to the hippocampus, which supports conscious allocentric space.
Medium of display: Gray regards consciousness as a medium of display created by unconscious processing. The standard objection to this is that it creates an infinite regress because there has to be a conscious homunculus viewing the display in the Cartesian theatre, and then an homunculus within that homunculus and so on ad infinitum. However, Gray argues that the conscious display is used by unconscious systems, as in the example of unconscious aversion to a food associated with a gastric illness. Conscious perception is in this theory created by unconscious systems, and used by other unconscious systems to respond to late errors, unexpectedness or novelty.
Consciousness – causal but without agency: Gray likens the conscious perception to a sketch made of a particular scene that is retained for use as a record or reminder of the scene. In this way, the sketch is causal in the sense that it performs the function of recalling or assisting memories, but it is not directly active in the brain. In Gray’s consciousness model, the conscious perception plays much the same role as the sketch in his analogy. Consciousness is causal, in the sense that downstream unconscious systems respond to it, mainly in the area of error correction. However, this conscious aspect of the brain has no agency or freewill with which to initiate or inhibit actions, anymore than the sketch on a piece of paper can initiate can initiate actions independently of our brain.
Incompleteness: I think that although there is much of interest in Gray’s analysis of intentionality, representation and the unconscious, his analysis is nevertheless incomplete in important ways. In discussing the unconscious nature of rapid response actions, he adopts the conventional but superficial approach to the Libet experiments. When he describes how these showed that trivial (automatic pilot type) actions are initiated in the brain before the awareness of the decision to make the action, he appears to simply assume without further discussion that this must apply to more deliberative or strategic decisions that by their nature takes a longer time to reach a conclusion.
In line with this, he also makes no extended to attempt to discuss either cognitive activity or the impact of emotions, and more importantly the interaction between the prefrontal cognitive areas and the areas of the brain processing emotions. It might be possible to argue there are unconscious systems making the actual decisions in these areas of the brain, but if Gray did want to establish this point, he needed to discuss his model in terms of these systems, which have a central role in determining actions. In particular, he needed to pin down the role of our subjective experience of emotion in determining preferences and actions, if he wanted to justify the dominance of the unconscious in actual decision taking.
What are qualia: Gray poses the question, as to how the brain creates and inspects the display medium of conscious perception. In asking this question, he makes the assumption that consciousness is different from either behaviour or brain activity. He views this as a ‘hard problem’, in the sense of the term coined by the philosopher, David Chalmers. He considers that for all of biology, except for the question of consciousness, the laws of physics and chemistry, plus natural selection and the internal feedback mechanisms selected for by natural selection are sufficient explanation. He considers that consciousness has sufficient causal effects to justify it being selected for by evolution. The hard problem is seen as being the difficulty of locating consciousness qualia within physics.
Amongst researchers within mainstream neuroscience, Gray is unusual in not finding the idea of quantum states being relevant to neural activity as ridiculous. However, his discussion of the Penrose’s version of the theory is not really complete, in that he concentrates entirely on Hameroff’s propositions for quantum activity in the brain, rather than Penrose’s original reason for looking to the quantum level in the first place. Penrose’s suggestion was that a special form of quantum wave reduction was the only thing that could explain mathematical understanding, when it goes further than what can be determined by the axioms of any formal theorem. This might been seen to answer one of Gray’s main objections to the theory, which is as to why particular wave function collapses should select for any one particular qualia. Gray also questions the temporal aspect of Hameroff’s model, where the proposed 25 milliseconds to wave function collapse equates to the 40 Hz gamma synchrony, which is possibly the best known correlate of consciousness. Gray argues that this does not work very well because it takes at least ten times as long as this for a conscious perception to form. However, this does not seem an insuperable problem given that there is strong support for the idea of a connection between gamma synchrony and consciousness. This is the case even in conventional neuroscience, which suggests some physical link between synchrony and the time to conscious perception, whether at the classical or the quantum level. Gray’s final word on the subject is that at least Penrose tries to explain qualia, which is seen as an advance on Dennett and functionalism, which essentially deny the data that we all have as to the existence of conscious experience or qualia, and which any valid theory of consciousness should attempt to explain rather than deny.Tags: hard problem, Jeffery Alan Gray Posted by