Current wisdom says that you can raise your IQ from 5-15 points or more depending on when you begin. Conversely, heavy multitasking can temporarily lower your IQ by 15 points. Not only that, estimates are that multitasking costs the global economy about $450 billion annually. And people keep trying to multitask because? Perhaps because they don’t know about the research or don’t really believe it or think their brains are uniquely exceptional or feel under pressure to do so or . . . fMRI studies by neuroscientists Etienne Koechlin and Sylvain Charron of the French biomedical research agency INSERM in Paris, showed that the human brain the brain can't effectively handle more than two complex, related activities at the same time. The brain has two hemispheres. When the brain tries to do two things at once, it assigns about half of its gray matter to each task. You can talk while you walk (but reading while you walk has been dubbed “distracted walking” and increases one’s risk of injury) or read while you eat (although you may spill stuff on your book or iPad) because the function of automaticity helps out. Try to pound nails while holding a conversation on an unrelated topic, however, and you may put your thumb at risk; try to use power tools while watching TV and you may put life or limb at risk. More tomorrow.