The Flynn effect, Jonah Lehrer notes, has always been tinged with mystery:
Some measures of intelligence — such as performance on Raven’s Progressive Matrices in Des Moines and Scotland — have been increasing for at least 100 years. What’s most peculiar is how scores have increased:
- Scores have increased the most on the problem-solving portion of intelligence tests.
- Verbal intelligence has remained relatively flat, while non-verbal scores continue to rise.
- Performance gains have occurred across all age groups.
- The rise in scores exists primarily on those tests with content that does not appear to be easily learned.
What’s puzzling about this increase in general intelligence is that it appears where we’d least expect it. While one might assume that IQ scores could increase over time in terms of crystallized intelligence — the part of the test that measures particular kinds of knowledge, such as being able to count or vocabulary words — it’s actually increased on measures of fluid intelligence, which is the ability to solve abstract problems.
Apparently the Flynn effect isn’t simply a matter of the lower-classes getting increased access to good nutrition and school — and less exposure to lead and other toxins. The top 5 percent are also scoring higher, which suggests some new form of environmental stimulation is boosting liquid intelligence:
Even for those on the right side of the curve, intelligence gains probably have many distinct causes, from the complexity of The Wire to the social multiplier effect, which is the tendency of smart people to hang out with other smart people. (In this sense, gifted programs in schools might help drive IQ gains among the top five percent. The Internet probably helps, too.) The question, of course, is whether such factors have really changed over time. Has it gotten easier for smart people to interact with each other? Are those on the right side of the IQ distribution now more likely to have children together? Would the Flynn effect be even larger if we did more of [fill in the blank]? These questions have no easy answers, but at least we now know that they need to be answered.
I don’t think you need to point to smart TV to explain this, as even I Love Lucy and Gilligan’s Island reruns are challenging for children who might otherwise be outside throwing rocks and swinging sticks. Those shows were mainstream adult fare when they first appeared on the air.
Al Fin lists a number of hypotheses:
Explanations for the Flynn Effect generally range from better nutrition, increased literacy, higher use of abstract thinking as populations increasingly move into urban environments, and even the greater use of Caesarean section in childbirth!
One unusual explanation for the Flynn Effect is a higher incidence of Asperger’s variant of autistic spectrum disorder. Another interesting explanation given is the relatively accelerated physical development of youngsters today as opposed to youngsters half a century or more ago. Earlier onset of puberty in modern times is a partial support for this argument. If this is true, comparison of today’s 12 year olds’ scores to the scores of 12 year olds several decades ago, would not be valid. (more here)