Who's in Charge?

September 12, 2011
Are our actions determined solely by physical processes, or is the mind its own master? This age-old philosophical conundrum gets a terrific, if ultimately indecisive, analysis in this engrossing study of the mechanics of thought. Gazzaniga (Human: The Science Behind What Makes Your Brain Unique), a leading cognitive neuroscientist, draws on cutting-edge research, including his fascinating experiments with “split-brain” patients, to diagram the Rube Goldberg apparatus inside our skulls. Beneath our illusion of an in-control self, he contends, thousands of chaotically interacting neural modules governing motion, senses, and language unconsciously make decisions long before we consciously register them; the closest thing to a self is a brain module called “the interpreter,” which spins a retrospective story line to rationalize whatever the nonconscious brain did. (Brain injuries can make the interpreter tragicomically muddled, leading patients to claim that their hand doesn’t belong to them or that their relatives are imposters.) The author’s reconciliation of that deterministic model with the idea of free will is less successful, requiring “a unique language, which has yet to be developed”; until then, we can only invoke muzzy notions from complexity theory. Though he doesn’t quite capture the ghost, Gazzaniga does give a lucid, stimulating primer on the machine that generates it. B&w illus.