There's been a pretty remarkable increase of 18 points in average IQ since the 1950s - more evidence that IQ is a function of both genetics and environment. But what does this mean? James Flynn explores the idea that intelligence is a function of different cognitive skills that can change independently of each other:

Once you break intelligence down into its autonomous components, many things become clear. For example, the Nation’s Report Card shows that today’s children are ahead of their parents in reading at early ages and then the gains fade away by the age of 17. How is that possible? The children are doing much better on heavily g loaded IQ tests like the WISC at all ages. Should not brighter people be able to read adult novels better?

This mystery is solved when you look at IQ trends over time. Since 1972 (when the NRC began), the big IQ gains have been on certain subtests and not others. There have been virtually no gains in vocabulary and information. You cannot enjoy War and Peace very much if you have to run to the dictionary or encyclopedia every other paragraph. We are doing a better job of teaching children the mechanics of reading at early ages. But their parents had mastered the mechanics by age 17 and at that age, neither generation has an information or vocabulary advantage. So we have made no progress is teaching young people how to enjoy adult literature.

Smarter and dumber. The more you analyze this subject, the more complex and interesting it becomes.

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