Consciousness: Creeping Up on the Hard Problem
by Jeffrey Gray
Via Wikipedia: "In his book Consciousness: Creeping up on the Hard Problem written towards the end of his life, Gray summarised his ideas about brain function and consciousness. He took the view that the contents of consciousness are usually about something, and this is described as intentionality or meaning. He suggested that 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 argued that without such binding, eating a banana could involve seeing yellow, feeling a surface, and tasting something, without having the unifying awareness of a particular object known as a banana. Without such unifying binding, he argues that objects would be just meaningless shapes, edges, colours etc.
Gray thought that intentionality was based on unconscious processing. The processing in the visual cortex that underlies conscious perception is not itself conscious. Instead, the perception is argued to spring into consciousness fully formed, including the intentionality of what the conscious perception is about. In arguing for this, Gray uses the example of pictures that can be either of two things, such as a duck or a rabbit. They are never hybrid, but are always completely duck or completely rabbit. The perception of a duck or a rabbit is argued to be constructed unconsciously up to the last moment. 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. [...]
Gray disagreed with the functionalist theory of consciousness. He described the position of functionalism as saying that consciousness is the nature of certain complex systems, regardless of whether they are made of neurons, silicon chips or some other material. The underlying tissues or machinery are 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 not functional. 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.
In discussing this question further, Gray looked at synaesthesia, where he described modalities as becoming mixed, as when numbers or sounds are experienced with colour. Experimentation in recent years has demonstrated that synaesthesia 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 have shown that when words are 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 does 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 experiments was that the 'word-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.
Gray argued from these findings that there was no relationship between the occurrence of the synaesthete's colour experience and the linguistic function that triggers them. Gray argues that this phenomenon refutes the functionalist analysis of consciousness, because the theory claims that conscious experience relates only to functions performed in the brain, and does not arise as a result of anything that is not functional, as is claimed to be the case with this type of synaesthesia."
Thanks to Constantin Rothkopf!