A stratospheric IQ predicts more worldly success than just a superhigh one, say researchers. That, they say, undermines the "threshold effect": the notion that IQ scores above, say, 130 don't matter because at those levels, other traits such as motivation and creativity distinguish people.
Scientists at Vanderbilt University in Nashville, Tennessee, looked at the careers of precocious youths who had aced the math SAT, an IQ-like test, at the age of 13. Using data collected when the subjects were 33, the researchers compared the top and bottom quartiles--covering about 1000 subjects--of those who scored in the top 1% of the math SAT on four indicators: advanced degrees, salaries, patents, and tenure at a top U.S. university.
In a paper in press at the Journal of Educational Psychology, the researchers report that the top quartile usually come out ahead: 32.1% got Ph.D.s, compared with 20% in the bottom quartile. For patents, it was 7.5% versus 3.8%; for tenure, 3.2% versus 0.4%. The highest scorers also made more money. The findings make sense in view of the fact that "the top 1% contains one-third of the ability range," says Vanderbilt's David Lubinski. For example, everything over 137 is in the top 1% of IQ scores, but IQs can go beyond 200.
Psychologist Joseph Renzulli of the University of Connecticut, Storrs, a proponent of the threshold effect, says he remains unconvinced. "Unless we can draw a perfect relationship between cognitive ability and creative productivity" in a wide range of people of above-average ability, "we must assume" that other factors are critical, he says.
