Case 1

THE FLYNN EFFECT
Given that a substantial amount of intellectual ability (up to 80 percent) is inherited, it might surprise you to learn that intelligence test scores are rising. In fact, scores have risen so dramatically that today's great-grandparents seem mentally deficient by comparison.

First, let's review the evidence for rising test scores. Then, we'll review explanations for the results.

On an IQ scale where 100 is the average, scores have been rising about 3 points per decade, meaning that if your grandparent scored 100, the average score for our generation would be around 115. That's a pretty big difference - about a standard deviation - meaning that someone who's from your grandparent's generation whose score was at the 84th percentile would only be average (50th) percentile by today's norms.

James Flynn is a New Zealand researcher credited with first documenting the rising scores. He first reported the results in 1984, when he found that almost everyone who took a well-validated IQ test in the 1970s did better than those who took it in the 1940s.

The results appear to hold up across cultures. Test scores are rising not only in the United States but in most other countries in which the effect has been tested, too.

What explains the Flynn Effect? Researchers are not entirely sure, but some of the explanations offered are:

1. Education. Students today are better educated than their ancestors, and education leads to higher test scores.

2. Smaller families. In 1900, the average couple had four children; today the number is less than two. We know firstborns tend to have higher IQs than other children, probably because they receive more attention than their later-born siblings.

3. Test-taking savvy. Today's Children have been tested so often that they are test savvy: They know how to take tests and how to do well on them.