Meehan Crist and Tim Requarth review James R. Flynn's new book, Are We Getting Smarter?: Rising IQ in the Twenty-First Century

If we were really getting smarter overall, scores should be going up across all the subtests, but that is not the case. To understand the score gains, then, we need to set aside issues of general intelligence and instead analyze patterns on the IQ subtests. 

What that analysis reveals:

As Flynn demonstrates, a typical IQ test question on the abstract reasoning “Similarities” subtest might ask “How are dogs and rabbits alike?” While our grandparents were more likely to say something along the lines of “Dogs are used to hunt rabbits,” today we are more likely to say the “correct” answer, “Dogs and rabbits are both mammals.” Our grandparents were more likely to see the world in concrete, utilitarian terms (dogs hunt rabbits), but today we are more likely to think in abstractions (the category of “mammal”). In contrast, the Arithmetic IQ subtest and the Vocabulary IQ subtest—tests that rely on previous knowledge—show hardly any score increase at all.

Previous Dish on Flynn's book here and here.