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See Inside April/May 2008

MIND Reviews: April/May 2008

Reviews and recommendations from the April/May 2008 issue of Scientific American MIND

YOU NEVER KNOW

ON BEING CERTAIN: BELIEVING YOU ARE RIGHT EVEN WHEN YOU'RE NOT
by Robert A. Burton. St. Martin Press, 2008. ($24.95)

The day after the 1986 Challenger shuttle accident, psychologist Ulric Neisser asked 106 students to write down exactly where they were and what they were doing when they first heard about the explosion. When he interviewed the students two and a half years later, 25 percent of them gave strikingly different accounts. But when confronted with their original journal entries, many students defended their beliefs. One of them answered, “That’s my handwriting, but that’s not what happened.”

In On Being Certain, neuroscientist and novelist Robert A. Burton tries to get to the bottom of the curious sensation he calls the “feeling of knowing”—being certain of a fact despite having no (or even contrary) evidence. Throughout his book, Burton makes the compelling argument that certainty “is neither a conscious choice nor even a thought process.” Instead, he says, that unmistakable sense of certainty “arises out of involuntary brain mechanisms that, like love or anger, function independently
of reason.”

Burton thinks that just as we perceive our external world through our physical senses, our internal world presents itself in the form of feelings, such as familiar or strange and correct or incorrect. And he shows that these inner perceptions are necessary for us to function properly in everyday life, because our thoughts are subject to constant self-questioning. For example, even though reason may tell us that running up a tree to escape a lion is an excellent strategy, experience shows that great strategies can fail and that there may be better options. Because alternative choices are present in any situation, logical thought alone would be doomed to a perpetual “yes, but” questioning routine. Burton reasons that it is the feeling of knowing that solves this dilemma of how to reach a conclusion. Without this “circuit breaker,” indecision and inaction would rule the day.

One of the startling implications of Burton’s thesis is that we ultimately cannot trust ourselves when we believe we know something to be true. “We can’t afford to continue with the outdated claims of a perfectly rational unconscious or knowing when we can trust gut feelings,” he writes. On Being Certain challenges our understanding of the very nature of thought and provokes readers to ask what Burton calls “the most basic of questions”: How do we know what we know?

NEURAL GEOGRAPHY

BEYOND THE ZONULES OF ZINN: A FANTASTIC JOURNEY THROUGH YOUR BRAIN
by David Bainbridge. Harvard University Press, 2008. ($25.95)

When David Bainbridge, a University of Cambridge anatomist, witnessed through ultrasound his daughter’s gestation, he was unexpectedly moved. Mesmerized by the detailed images of her budding nervous system, he saw in her eyes a tiny ring of fibers encircling each lens, known as the zonules of Zinn.

This experience spurred him to write Beyond the Zonules of Zinn, a tale of the brain by a physiologist. Because form often gives insight into function, he uses evolutionary biology to walk us through human gestation, explaining how natural selection favors genes that enhance functions critical to survival, which often later give rise to specialized anatomical features. In the brain we find spectacular geographic specificity, where tiny patchworks of neurons give us language, planning and vision.

Even in a nine-week-old human fetus, a primitive nervous system emerges. Bainbridge explains how a neural bud bulges into a forebrain, midbrain and hindbrain, culminating in the cerebral cortex—the creviced, convoluted tissue layer that makes up the brain’s surface. On the evolutionary trail, he describes how primitive drives (such as hunger, sex and sleep) evolved into higher functions, including memory, learning and emotions.
Gender differences, brain size, intelligence and even bizarre teenage behavior all have underpinnings in neural anatomy. Bainbridge marvels at how the fragile sheet of the cerebral cortex organizes our sensations, leading naturally to consciousness. In contrast to philosophical speculations on consciousness, Bainbridge focuses on neural hardware. Distilling seven leading theories of consciousness, he argues that consciousness is material, not mystical—something “our brain does.”

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