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Mindful : June 2015
Chicago psychologist Sia n Beilock, a leading expert on choking, explained it this way: “When a skill is well learned, there should be less activation of the prefrontal cortex”—the region involved in planning and conscious decision-making. Consciously focusing on a task, however, produces the opposite: more activation of the prefrontal. In one of Beilock’s favorite laboratories—the putting green—she showed how focusing ca n trigger a choke. When tyro golfers consciously call up the individual motions involved in a golf swing, through intense prefrontal activation, they do better. They’re learning. But when experienced golfers do, they miss—which, if it occurred in a tournament rather than a lab, would be called choking. Overactivation of the prefrontal seems to mute circuitry that holds implicit knowledge (especially how-to, or motor, knowledge), such as riding a bicycle or, for expert golfers, putting. When we think uh-oh , pressured situation, let me make sure I do everything right, we bench the brain’s implicit system a nd send the klutzy, prefrontal-driven explicit system up to the plate. No wonder it whiffs: think how much less smoothly you would, say, shower if you had to hyper-consciously think about each step (raise hand to shower door; push open; grip faucet...) rather than act automatically. Consciously activating each sequential ele- ment of an athletic movement or argument (as Governor Perry did) makes us choke. A 2012 study led by neu- roscientists at Caltech and published in Neuron showed how stress sidelines circuits encoding implicit expertise. They had volunteers try to move a virtual ball, tied to a virtual string, into a square target on a screen within two seconds, all while their brain activity was being measured by functional MRI. Performance improved as the prizes became more valuable, but soon it crashed: high-value rewards hurt performance and the subjects began to choke. The fMRI showed why: A subcortical region called the ventral striatum, which pro- cesses the value of pleasures as varied as eating ice cream and receiving cash, became more active at the prospect of higher fina ncial stakes. But after a certain point the activity took a U-turn: higher prizes were associated with lower ventral striatum activ- ity. Here’s why that matters: the ventral striatum is also known to help control move- ment. Sure enough, the less activity in the striatum, the worse the volunteers’ ability to control the virtual ball. The perils of drifting away from the brain’s implicit-knowledge sys- tems received fascinating experimental support when scientists in Germany found a clever way to prevent it: squeezing a ball. The resea rchers had soccer players, judo experts, and badminton aces first prac- tice and then, upping the stress, play before a crowd or camera. The idea was to German scientists discovered a clever way to prevent the brain from drifting away at key moments: squeeze a ball. 20 mindful June 2015 brain science