Editing Intelligence quotient (section)

===United States military selection in World War I===
During World War I, the Army needed a way to evaluate and assign recruits to appropriate tasks. This led to the development of several mental tests by [[Robert Yerkes]], who worked with major hereditarians of American psychometrics—including Terman, Goddard—to write the test.<ref name=Gould>{{harvnb|Gould|1996}}</ref> The testing generated controversy and much public debate in the United States. Nonverbal or "performance" tests were developed for those who could not speak English or were suspected of malingering.<ref name=Kaufman2009/> Based on Goddard's translation of the Binet–Simon test, the tests had an impact in screening men for officer training:

<blockquote>...the tests did have a strong impact in some areas, particularly in screening men for officer training. At the start of the war, the army and national guard maintained nine thousand officers. By the end, two hundred thousand officers presided, and two- thirds of them had started their careers in training camps where the tests were applied. In some camps, no man scoring below C could be considered for officer training.<ref name=Gould/></blockquote>

In total 1.75 million men were tested, making the results the first mass-produced written tests of intelligence, though considered dubious and non-usable, for reasons including high variability of test implementation throughout different camps and questions testing for familiarity with American culture rather than intelligence.<ref name=Gould/> After the war, positive publicity promoted by army psychologists helped to make psychology a respected field.<ref>{{cite book |first1=Carrie H. |last1=Kennedy |first2=Jeffrey A. |last2=McNeil |editor1-first=Carrie H. |editor1-last=Kennedy |editor2-first=Eric |editor2-last=Zillmer |year=2006 |chapter=A history of military psychology |chapter-url= https://books.google.com/books?id=rytCzdXGgXkC&pg=PA1 |title=Military Psychology: Clinical and Operational Applications |pages=1–17 |location= New York |publisher=Guilford Press |isbn=978-1-57230-724-7}}</ref> Subsequently, there was an increase in jobs and funding in psychology in the United States.<ref>{{cite journal |last1=Katzell |first1=Raymond A. |last2=Austin |first2=James T. |year=1992 |title=From then to now: The development of industrial-organizational psychology in the United States |journal=Journal of Applied Psychology |volume=77 |issue=6 |pages=803–35 |doi=10.1037/0021-9010.77.6.803}}</ref> Group intelligence tests were developed and became widely used in schools and industry.<ref name="Kevles, D. J. 1968">{{cite journal |last1=Kevles |first1=D. J. |title=Testing the Army's Intelligence: Psychologists and the Military in World War I |journal=The Journal of American History |volume=55 |issue=3 |pages=565–81 |year=1968 |doi=10.2307/1891014 |jstor=1891014}}</ref>

The results of these tests, which at the time reaffirmed contemporary racism and nationalism, are considered controversial and dubious, having rested on certain contested assumptions: that intelligence was heritable, innate, and could be relegated to a single number, the tests were enacted systematically, and test questions actually tested for innate intelligence rather than subsuming environmental factors.<ref name=Gould/> The tests also bolstered [[Jingoism|jingoist narratives]] opposing the high rates of immigration at the time, which may have influenced the passing of the [[Immigration Act of 1924|Immigration Restriction Act of 1924]].<ref name=Gould/>

[[Louis Leon Thurstone|L.L. Thurstone]] argued for a model of intelligence that included seven unrelated factors (verbal comprehension, word fluency, number facility, spatial visualization, associative memory, perceptual speed, reasoning, and induction). While not widely used, Thurstone's model influenced later theories.<ref name=Kaufman2009/>

[[David Wechsler]] produced the first version of his test in 1939. It gradually became more popular and overtook the Stanford–Binet in the 1960s. It has been revised several times, as is common for IQ tests, to incorporate new research. One explanation is that psychologists and educators wanted more information than the single score from the Binet. Wechsler's ten or more subtests provided this. Another is that the Stanford–Binet test reflected mostly verbal abilities, while the Wechsler test also reflected nonverbal abilities. The Stanford–Binet has also been revised several times and is now similar to the Wechsler in several aspects, but the Wechsler continues to be the most popular test in the United States.<ref name=Kaufman2009/>