If someone starts to use his inner voice and simple math all the time his IQ would most likely increase a lot, won't it? Even if he is a dumb, after a few days his inner voice will help him to properly analyze and solve problems. Those IQ tests are just that, they are not difficult and there is nothing novel to them, the patterns obvious to anyone that actually thinks. Its more about enabling your brain and not being on an autopilot. Don't get me wrong, there can be brutal tresholds between people but we are very far from this being a reality. The brain and the thinking abilities really are like a muscle.