Raymond Cattell once distinguished the following two aspects of intelligence: 1) fluid and 2) crystallized intelligence. Fluid intelligence is the capacity to think logically and solve problems in novel situations, independent of acquired knowledge. Crystallized intelligence is the ability to use skills, knowledge, and experience.
Many psychologists have long thought that crystallized intelligence can be developed but fluid intelligence can't be developed. And many still do. But cracks begin to show in the believe that fluid intelligence can't be developed. Previously, I have already mentioned a study by Jaeggi, Buschkuehl, Jonides, and Perrig (2008) which shows fluid intelligence is trainable for anyone and the more you train, the more you gain. Here is another challenge to the idea that fluid intelligence is not mutable.
University of Michigan psychologist John Jonides presented new findings showing that practicing little exercise called n-back training for about 20 minutes each day for 20 days significantly improves performance on a standard test of fluid intelligence. And this improvement lasted for up to three months.