Lewis Terman, the inventor of the Stanford-Binet IQ test, came to a similar conclusion. He spent decades following a large sample of “gifted” students, searching for evidence that his measurement of intelligence was linked to real world success. While the most accomplished men did have slightly higher scores, Terman also found that other traits, such as “perseverance,” were much more pertinent. Terman concluded that one of the most fundamental tasks of modern psychology was to figure out why intelligence is not a more important part of achievement: “Why this is so, and what circumstances affect the fruition of human talent, are questions of such transcendent importance that they should be investigated by every method that promises the slightest reduction of our present ignorance.”
Unfortunately, in the decades following Terman’s declaration, little progress was made on the subject. Because intelligence was so easy to measure - the IQ test could be given to schoolchildren, and often took less than an hour - it continued to dominate research on individual achievement.
The end result, says James J. Heckman, a Nobel Prize-winning economist at the University of Chicago, is that “there was a generation of social scientists who focused almost exclusively on trying to raise IQ and academic test scores. The assumption was that intelligence is what mattered and what could be measured, and so everything else, all these non-cognitive traits like grit and self-control, shouldn’t be bothered with.”