It’s hard to prove that the conscious mind is located in the brain. One problem is that both mind and brain are incredibly complicated, and it’s hard to map one sort of complexity onto the other. Popular media sometimes imply that science has accomplished this feat, but this isn’t so.
Suppose we ask subjects to visualize a square, then a circle, then a square again, while their brains are scanned for signs of neural activity. And suppose this experiment enables us to print out colorful pictures showing that brain regions 1-2-3 are especially active while subjects visualize squares, and regions 4-5-6 are especially active while they’re imagining circles. Does this show that the experience of fantasizing squareness is located in 1-2-3 and fantasizing circularity is located in 4-5-6?
Not at all. It’s a start, but barely that, and I’ll just mention two of the many difficulties.
1. How much of a lit-up region is the experience of the item, and how much of it is a motley assortment of non-experiential accompaniments? Visualizing a square may call up all sorts of associations with square items and with the word “square” – square meal, square deal, square mile, and “you’re so square.” Perhaps activity in linguistic regions involves verbal associations only, and is never part of the mental image itself. Perhaps. But we don’t know for sure.
2. It’s also hard to know which aspects of a brain’s activity are conscious processes and which are the unconscious accompaniments. A great deal of the brain’s visual processing, for example, never reaches the level of awareness.
Someday we may be able to detect precisely which neural activities constitute, say, a visual experience of seeing a single cherry blossom, but this will certainly not be easy. Compare the task of identifying precisely which electromagnetic waves in the signal from a TV satellite constitute an image of the seams of a football being passed during the last five seconds of the 2015 Superbowl. We assume that this part of the video signal is a physical event, and our inability to precisely specify it does not make us philosophically puzzled. But the difficulty of knowing just which brain activities constitute a particular experience may make us wonder whether this experience could be in the brain. Complexity confuses us, so beware of the complexity trap.
I recall a lecture in which the speaker announced that he was going to display his model of the neural correlates of consciousness, or NCC. The NCC is whatever cluster of neural activities correlates with conscious experiences, and finding such a correlation would be a big step toward showing that experiences are constituted by neural processes. He then showed us a diagram with about 50 arrows going in all sorts of directions.
He was joking, of course, because we have no idea how to sketch the NCC. We need to remind ourselves that the brain is much more complex than we can comprehend, and that we are in this convoluted mish-mash.
Roger Christan Schriner