Richard Tomkins reviews What is Intelligence? Beyond the Flynn Effect by James R. Flynn, in the Financial Times:
A more precise, if less exciting, title for this book might have been What is Intelligence Testing? since that is what it is mainly about. But don’t let that put you off. This is a mystery story – and an intriguing one.
In the early 1980s, the author, a US-born psychologist now living in New Zealand, made the startling discovery that, over the course of the 20th century and across the developed world, IQ test scores had shown big gains from one generation to the next. This phenomenon, which became known as “the Flynn effect”, had previously gone unnoticed because test scores were continually normalised to keep the mean at 100.
Picking up the story in this book, James Flynn notes that the phenomenon throws up several paradoxes. If people really are becoming more intelligent, why are we not struck by the extraordinary cleverness of our children or the stupidity of our parents? If, by present-day norms, the average IQ score in 1900 was between 50 and 70, are we to accept that most of our ancestors were, literally, mentally retarded?
And if, as has been shown over and again, genes dominate individual differences in IQ, how do we reconcile that with sudden leaps in IQ from parent to child? Why, as IQ scores rise, are people getting no better at arithmetic, vocabulary or general knowledge?