An interesting fact has emerged from IQ testing over the past 60 years: Scores have risen so dramatically and so quickly that scientists say heredity cannot be the cause.
Because IQs are always adjusted into a bell-shaped curve, with an IQ of 100 being the mid-point, the rise in raw scores has not been readily apparent.
But researchers for 10 years now have been giving subjects IQ tests that had been unchanged for almost all of the last century.
The results show that today’s American children would perform 20 points higher in IQ on the scale given in 1931.
Today, about 25 percent would rank as intellectually superior on that 1931 test, when only 3 percent fell into the category at that time.
Scientists offer a variety of possible reasons behind the rise in IQs:
- better nutrition,
- improved child-rearing in smaller families,
- more exposure to schooling and testing,
- the bombardment of media stimulation,
- and modern teaching techniques.
They all agree that heredity could not account for the rise.
IQ tests measure intelligence, abstract reasoning, or mental sharpness, and scientists say this is apparently more responsive to changes in the way we live than to our genetic makeup.
Living in a richer, more stimulating environment may not make people wiser, kinder, or more accomplished on tests of recall. But it does seem to make them smarter in the ways that intelligence tests can record.