As Descartes almost invented the idea of consciousness about 400 years ago, it is no wonder that his notion of what consciousness is has become deeply embedded in our culture. He famously said ‘cognito ergo sum’ which is usually translated as ‘I think, therefore I am’ but a better translation, in the context of his philosophy, would be ‘I introspect, therefore I am’. He thought that introspection gave us the only direct knowledge of anything (in this case our own thoughts) because the knowledge did not pass through the error prone sensory processes. This was the bedrock on which he built his philosophy. To Descartes there were two sorts of things: material things that took up space and consciousness that took up no space (was immaterial). This dualism has the problem of interaction between mind and body. Is everything actually mind (idealism) or is everything actually body (materialism) or do both exist and interact or do both exist and not interact? Dualism say both exist and has tried (in vain, I would say) to figure out how they interact or how they correspond if they do not interact. A lot of weird and wonderful philosophy has come out of this problem. G. Ryle called Cartesian Dualism ‘the dogma of the Ghost in the Machine’.
The long standing habit of imagining the mind as a THING as opposed to a process forces the idea that it is an immaterial thing. We, after all, cannot find this thing or the space it occupies etc. But if the mind is not a THING, it can be a process that is carried out by material things and there is no problem.
We have experimental evidence that our knowledge of our own thoughts via introspection is not direct and without error. But the idea of an immaterial mind is so deep in our culture that sometimes the experimental evidence appears paradoxical even to the researchers familiar with it. We are in the middle of a real paradigm shift here it is not mind verses matter, it is matter doing mind as a physiological function. We do not say ‘where is the digestion?'; can’t find the thing; so digestion must be immaterial. We say digestion is a physiological function of the alimentary canal. Mind is a function like digestion, circulation, immunity etc.