TIME : Risk (Perception : Part 2 of 6)

Friday, March 30, 2007

AN OLD BRAIN IN A NEW WORLD

Part of the problem we have with evaluating risk, scientists say, is that we’re moving through the modern world with what is, in many respects, a prehistoric brain.  We may think we’ve grown accustomed to living in a predator-free environment in which most of the dangers of the wild have been driven away or fenced off, but our central nervous system–evolving at a glacial pace–hasn’t got the message.  To probe the risk-assessment mechanisms of the human mind, Joseph LeDoux, a professor of neuroscience at New York University and the author of The Emotional Brain, studies fear pathways in laboratory animals.  He explains that the jumpiest part of the brain–of mouse and man–is the amygdala, a primitive, almond-shaped clump of tissue that sits just above the brainstem.  When you spot potential danger–a stick in the grass that may be a snake, a shadow around a corner that could be a mugger–it’s the amygdala that reacts the most dramatically, triggering the fight-or-flight reaction that pumps adrenaline and other hormones into your bloodstream.  It’s not until a fraction of a second later that the higher regions of the brain get the signal and begin to sort out whether the danger is real.  But that fraction of a second causes us to experience the fear far more vividly than we do the rational response–an advantage that doesn’t disappear with time.  The brain is wired in such a way that nerve signals travel more readily from the amygdala to the upper regions than from the upper regions back down.

Setting off your internal alarm is quite easy, but shutting it down takes some doing.  “There are two systems for analyzing risk: an automatic, intuitive system and a more thoughtful analysis,” says Paul Slovic, professor of psychology at the University of Oregon.  “Our perception of risk lives largely in our feelings, so most of the time we’re operating on system No. 1.”…..These two impulses–to engage danger or run from it–are constantly at war and have left us with a well-tuned ability to evaluate the costs and payoffs of short-term risk, say Slovic and others.  That, however, is not the kind we tend to face in contemporary society, where threats don’t necessarily spring from behind a bush.  They’re much more likely to come to us in the form of rumors or news broadcasts or an escalation of the federal terrorism-threat level from orange to red.  It’s when the risk and the consequences of our response unfold more slowly, experts say, that our analytic system kicks in.  This gives us plenty of opportunity to overthink–or underthink–the problem, and this is where we start to bollix things up.

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