People have been studying for years about what is intelligence, what part of the brain is involved in “intelligence”, and how can we measure it? In general, intelligence is the ability to learn and to recall or remember what we have learned. In the 1960’s it was suggested that there were two “systems” of intelligence, fluid intelligence and crystallized intelligence. Fluid intelligence involves the ability to understand, to reason and to solve problems. Crystallized intelligence involves recalling stored knowledge and past experiences