Many times on this blog I have claimed that the correlation between IQ and years of educations (indeed IQ and academic success in general) is 0.65. I have based many arguments on this figure which I had assumed was correct since it came from none other than the late great Arthur Jensen who cited it on page 279 of his 1998 book The g Factor. Well it turns out the figure is no longer true, and hasn’t been true for at least several decades. The standardization sample of adults (age 25+) on the WAIS-III revealed the correlation between full-scale IQ and years of education has sunk to 0.55. It seems back in the 1950s, when the first WAIS was standardized, the correlation between IQ and years of education was about 0.7, but by 1978, when the revised WAIS was normed, it had already sunk to the mid 0.5s.
This may not seem like a big difference, but imagine people who average more education than 99.5% of America (i.e. PhDs today) and people who average less education than 99.5% of Americans (8th grade dropouts?). These groups theoretically differ by 5 standard deviations in education, so if the correlation between IQ and education were still 0.7, they would in theory differ by 0.7(5 SD) = 3.5 SD in IQ (54 IQ points!). Instead, with a correlation of 0.55, they differ by “only” 0.55(5 SD) = 2.75 SD (43 IQ points!).
So what’s happening is academic elites have becomes dumber, and academic failures have becoming smarter (relative to the U.S. population average).
This is the exact opposite of what we were told by the book the The Bell Curve which argued that society was becoming more and more stratified by cognitive ability. But it seems with respect to education, we’ve become cognitively less stratified.
This is consistent with data suggesting that the average IQ at Harvard is “only” around 122. Don’t get me wrong, 122 is a very high IQ, and much higher than the U.S. average of 97, and the World average of 90. But you’d expect students at the most prestigious university on the face of the planet to be at least Mensa level (IQ 128+). The fact that they may “only” average 122, is consistent with IQ and academic success no longer being strongly linked.
Why is this happening? I can think of two possible reasons (both speculative):
1) IQ tests are getting more accurate. In the past IQ tests were biased in favour of educated people, but as psychologists improved the test administration so that even high school dropouts and illiterates could understand the instructions, the tests became more fair to everyone, and the gap in test scores between the educated and uneducated shrunk. In other words, the link between IQ and academic success was spuriously high in the past, and more accurate testing has now corrected the error.
2) Getting educated is no longer the smartest thing to do. In the past, the best way to get rich was to become a doctor or a lawyer or join some other overeducated profession. But with the explosion of income inequality, even college dropouts can start a business and become a hundred times richer than most lawyers. Since smart people understand the value of money and can figure out where to get it, many high IQ people decided to skip college and gamble on their own business, causing the correlation between IQ and education to drop.