When children learn to count, for instance, they show gains on crystallized intelligence, even as their fluid intelligence remains constant.
At the end of each training, researchers tested theparticipants' fluid intelligence again.
And yet these schoolchildren showed gains in fluid intelligence roughly equal to five IQ points after one month of training.
Specifically, they improved their performance on tests of so-called fluid intelligence, the ability to solve new problems and reason abstractly.
In particular, a quality called "fluid intelligence" -including numerical skills and the ability to adjust rapidly to new situations-begins to go downhill in middle age.
