A Sharper Mind, Middle Age and Beyond - NYTimes.com

A Sharper Mind, Middle Age and Beyond - NYTimes.com: Many researchers believe that human intelligence or brainpower consists of dozens of assorted cognitive skills, which they commonly divide into two categories. One bunch falls under the heading “fluid intelligence,” the abilities that produce solutions not based on experience, like pattern recognition, working memory and abstract thinking, the kind of intelligence tested on I.Q. examinations. These abilities tend to peak in one’s 20s.

“Crystallized intelligence,” by contrast, generally refers to skills that are acquired through experience and education, like verbal ability, inductive reasoning and judgment. While fluid intelligence is often considered largely a product of genetics, crystallized intelligence is much more dependent on a bouquet of influences, including personality, motivation, opportunity and culture.