Gardner, Extraordinary Minds, 39
The relationship between early reading and high psychometric intelligence is worth nothing. The connection is not essential–there are early readers who are not otherwise bright (and some of whom may even be brain-damaged); and there are certainly high-testers who read at a normal age or are even delayed at the onset of literacy. Still, our conception of scholastic intelligence is integrally tied to the capacity to master arbitrary notations and to use them speedily and flexibly. Mastery of print is an early way of demonstrating this facility. And so it is not surprising that youngsters with IQs above 170 are twice as likely to read by age four as those whose IQs fall below that level.