Brainy mind

The primary question is whether the brain receives or makes sensations. When we look at grass: is the sensation of green picked up by the eyes, from light reflected from the grass, or is the sensation, the qualia of green, created in our brains? It is now as certain as anything—as Isaac Newton appreciated three centuries ago—that light itself has no colour. Light evokes colour in suitable eyes and brains, which is very different. And violins have no sounds without ears and brains to create sound qualia. Recently the brain scientist Semir Zeki located colour creating cells in the brain (in the visual area of the striate cortex V4). One can imagine a bunch of interacting robots getting on fine without any awareness of qualia; but surely they wouldn’t spend hours looking at pictures, or listening to Beethoven. This is just how behaviourist psychologists a few years ago described us—as lacking consciousness, or qualia of red or pain or the sound of violins. Why an audience without music qualia would sit through a symphony was hardly questioned. Now, psychology has abandoned the behaviourism of J B Watson and B F Skinner, who tried to make psychology seem more scientific and less whimsical by denying consciousness. The situation is reversed so that physicists, especially Roger Penrose, are asking how the physical world can have consciousness. And the brain is very generally seen as a physical system obeying physical laws. Consciousness is a hot scientific topic. Philosophers such as Daniel Dennett and Paul and Patricia Churchland, as well Francis Crick, discuss from the basis of detailed knowledge of neurophysiology and brain anatomy how the mind can be brainy. It remains mysterious how physical stimuli affecting the physical brain give us, and presumably at least the higher animals, the consciousness of qualia. If qualia affect the nervous system, how can chemistry and physiology give adequate explanations of behaviour and of how the brain works? Yet why should consciousness have evolved if it is useless? The key notion of cognitive psychology since the collapse of behaviourism is that we build brain descriptions of the world of objects, which give perception and intelligent behaviour. Perceptions are not regarded as internal pictures or sounds, but rather as language-like descriptions coded, we suppose, by brain structures of what may be out there. We carry in our heads predictive hypotheses of the external world of objects and of ourselves. 2 These brain-based hypotheses of perception are our most immediate reality. But they entail many stages of physiological signalling and complicated cognitive computing, so experience is but indirectly related to external reality. From patterns of stimulation at the eyes and ears and the other organs of senses, including touch, we project sensations of consciousness into the external world. Although this is a startling thought, the experience of projecting afferent reality from the eyes is familiar in visual after-images. Try looking at a bright light, then at a surface such as wall. You see the pattern that is photographed on the retina from the flash as outside the eye, as being on the wall. The more distant the surface the larger it appears, though of course the retinal photograph is unchanged. This startling notion that perception is projecting brain-hypotheses outwards into the physical world—endowing the world with colour and sound and meaning—has surprising implications.