Rising Scores on Intelligence Tests
Test scores are certainly going up all over the world, but whether intelligence itself has risen remains controversial
When societies modernize, child-rearing practices change along with everything else. Parents everywhere are now interested in their children's intellectual development and are probably doing more to encourage it than they did in the past. We have no systematic data on that point, but we do know that modern volumes of child-care advice are available almost everywhere. For instance, the works of Dr. Spock have been translated into dozens of languages, and millions of children spend hours every day watching Sesame Street and other educational programs. A principal purpose of all that early stimulation is to raise children's overall intelligence. Is there reason to believe that it has done so?
The effect of early childhood experience on IQ scores has been a vexed question for many years. We now know that preschool (age 3-4) intervention programs like "Head Start" do not produce lasting changes in IQ, although they do confer other important benefits. It is possible, however, that more intensive interventions earlier in childhood would produce more substantial effects. For example, in the North Carolina "Abecedarian Project"—an all-day program that provided various forms of environmental enrichment to 57 children from infancy onward (mean starting age 4.4 months) and compared their test performance to a matched control group—differences between groups became apparent before the end of the first year. The difference did not diminish over time; the IQ difference between the groups was still present at age 12. Nevertheless, even this very intensive intervention only resulted in a gain of five IQ points, and not all such projects have been successful. Thus it seems unlikely that changes in the intellectual character of early childhood experience can explain a major share of the Flynn gains.