Friday, September 12, 2008

Nick Humphrey: Seeing Red

Nick Humphrey's Seeing Red is another attempt to explain consciousness, but from a slightly different angle. Humphrey clearly understands what it would mean to produce an explanation, and makes some progress on the task. Humphrey starts not with what it means to think about something or to be aware of something, but with the more fundamental fact of perception of something outside of ourselves. The focal perception is of a red sensation. There's something in your environment that produces the perception of redness. What just happened to you? What does it mean that it makes you sense the presence of red? Why can you share this experience with others who also perceive the redness or with people who aren't present but still understand what you mean?

Humphrey first concentrates his attention on the internal details: first you perceive, then you become aware that you are perceiving. You may put words to the sensation or you might not, but Humphrey takes pains to point out that the perceiving and awareness are two separate facts. If you then talk to someone else about the perception (which you can do because you're aware of it), then of necessity each of you has some kind of "theory of mind"; a mental model that represents the fact that whatever it means to perceive, you are something that can do it, and other people are capable of the same thing.

Having set these aspects of reality out, Humphrey goes to some trouble to demonstrate that they are separate facets of reality, and all need to be present in an actual explanation. He talks about things like 'blindsight' and optical illusions in order to convince people who aren't keeping up that all these things are distinct facets of reality and need to be distinct in any explanation.

In the second half of this small book, Humphrey explains that consciousness arises out of the neurons in the brain, and that their role is to reflect and represent what's really going on in the world. He wants to present an evolutionary explanation of why they arose, but he only really justifies the fact that they are useful. The mechanism and history that allowed a feedback process between sensing and acting to arise and be passed down as a competitive advantage eludes him. And he doesn't have much to say about how the neural substrate might represent facts about reality in such a way that it could actually be useful to an aware, active agent interacting with the world.

My bottom line is that this book lays out the issues fairly clearly in a way that ought to be interesting and convincing to someone who is just starting to think about how consciousness might work, but the explanations fall short of answering the deeper questions. On the other hand, Humphrey's stated goal in the book is to show that consciousness matters and that it can be productive to think carefully about it. That much he succeeded at.

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