IQ scores have risen dramatically over the last few generations. Flynn, a psychologist who discovered this trend 25 years ago, takes a provocative look at what escalating scores mean for the death penalty, racial differences in IQ and other controversial social issues.
Flynn begins by reviewing IQ rises in developed countries. An average Dutch person in 1982, for instance, scored as a near genius relative to the Dutch of 1952. Formal schooling and more complex cultures sparked IQ inflation, Flynn says. Gains occurred largely on test items that gauge the ability to classify things using scientific terms, such as listing dogs and rabbits as mammals, and to use logic to solve hypothetical problems, such as determining how a sequence of abstract shapes will play out.
So people today are smarter than those in the past at dealing with complex, abstract problems, Flynn says. Perhaps modern societies have nurtured an analytical intelligence that contrasts with a past emphasis on practical smarts, he suggests.
As for IQ differences, Flynn criticizes psychologists for ignoring social forces as a shaper of intelligence along with genes and brains. For example, the role of some childhood exposures in observed racial differences in IQ scores has attracted almost no research.
Flynn’s book sometimes gets bogged down in details and cross-national data crunching. But he remains one of the most original thinkers in IQ testing.
Cambridge Univ., 2012, 310 p., $22