The new device works by tracking your brain-wave activity as you play games or engage in virtual-reality simulations. When synapses fire, they release electrical pulses that move through the body. The iPhone-size device uses three carbon contacts to tap the signal through the skin, while software filters out electrical interference from moving muscles, particularly the heart. The system comes with software, such as games or virtual-reality training scenarios, and it prevents you from engaging in any program until you’re in the zone.