It was once thought that intelligence or IQ was fixed for life. However, years of research by doctors and psychologists has lead to the discovery of the importance of relational skills to intelligence and it took several more years for scientists to figure out how best to teach these skills. Today we know that IQ can in fact be increased by quite a degree. There have also been considerable advances in neuroscience in recent years, that have led psychologists to conclude that the brain itself can be made “fitter” with training and can respond and adapt to improved learning opportunities. Even leading authorities, such as Professor Robert Sternberg, now agree that IQ can be raised.
No psychological research has ever FOUND that intelligence is fixed for life. Instead, tests for general and specific intellectual ability are developed in such a way that your score from one test take to another (say a year apart) will not change much. The simplest way in which this is achieved, is by masking the gain in your improvement over time by NOT calculating your real raw score on the test, but instead calculating your score in terms of how it compares relatively to people of your age. Because everyone of your age is improving intellectually at roughly the same rate, this way of scoring the IQ test creates the false impression that you are not getting any smarter. Indeed, the whole population is getting smarter (an effect known as the Flynn effect), but tests are regularly revised to make sure that this effect is disguised. The tests are designed in advance so that someone in the bottom 20 percent of the population, for example, will continue to score well below the average score as teh years go by. As the population becomes smarter, the gap closes between the raw score of someone on the 20th percentile and the average score of someone on the 50th percentile (always defined as a score of 100).
Newer revised tests serve the purpose of opening up the gap again to keep the low scorers scores down and away from the average score. This is intended to disguise the fact that the lowest scorers in the population are in fact doing much better than they were just a few years ago. Read an article on this here entitled... You can improve IQ