The Mismeasure of Man | Study Guide

Stephen Jay Gould

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The Mismeasure of Man | Chapter 5 : The Hereditarian Theory of IQ: An American Invention | Summary



Alfred Binet and the Original Purposes of the Binet Scale

Alfred Binet was the director of the psychology lab at the Sorbonne, a university in Paris. He began his study of intelligence with craniometry, as everyone else was doing. But, after publishing several studies in which he measured the heads of school children, he was no longer sure that Paul Broca and craniometry were right. Any differences in head size he found were so small as to be insignificant, and sometimes they contradicted the central tenet of Broca and his school—that smarter people have bigger brains. Finally, Binet realized that perhaps his preexisting beliefs about intelligence and head size were actually affecting the accuracy of his measurements. Although he wasn't doing it intentionally, Binet believed that he was inadvertently increasing the skull volume of smart students and decreasing that of less capable ones.

After this epiphany, Binet almost gave up his studies of intelligence. But after a few years away from the field, he returned with a new line of attack on the problem. He was tasked by the French government to develop a test to show which children in school needed extra help to keep up with other students. He didn't test reading or math skills directly. Instead, he came up with a series of daily tasks—such as counting money and looking at faces—that he believed indirectly tested a child's reasoning skills. Then he developed a scale to create a single number to rate a child's intelligence. He did this by arbitrarily stating that each task could be completed by a child of a certain age. The student being tested was given the "mental age" of the most complicated task he could perform, and this was compared to his actual chronological age. A German psychologist later decided that the mental age should be divided by the chronological age to produce the intelligence quotient: or the IQ, as it is known today.

Binet tried hard to develop a test that would rate native mental skills, not knowledge that a child might have acquired from books or school. But he was clear that he did not think he was measuring intelligence. That, he believed, was too complex a phenomenon for any test to accurately measure. He viewed IQ as merely a tool to help teachers figure out the best ways to help their students. Binet was deeply afraid that his test would be misused—children might be labeled as backward and teachers might give up on them. When Binet's IQ test was brought to the United States, his worst fears were realized.

Gould sees the misuse of IQ tests as being based in two fundamental errors: reification and hereditarianism. Reification means treating an abstract concept as if it were a real thing. Gould promises to discuss that in detail in Chapter 6, but he does say here that American psychologists made the mistake of reifying Binet's IQ scoring system and assuming it measured something real called intelligence.

Hereditarianism is an error because it equates inheritance with immutability. Gould does not dispute that mental ability is, to a certain extent, inherited, but just because something is inherited doesn't mean it is inevitable. Intelligence can and does change throughout a person's life—it is possible to alter or improve intelligence through things like nutrition and education. When American psychologists and educators encountered Binet's IQ test, they fell right into the hereditarian error.

H.H. Goddard and the Menace of the Feeble-Minded

H.H. Goddard was the director of the Vineland Training School for Feeble-Minded Girls and Boys in New Jersey and the man who coined the term "moron." He used it as a technical term to label people whose mental abilities were just below those of normal adults. Goddard embraced Binet's IQ tests, but in doing so, he made both the reification and hereditarian errors. Goddard believed that the IQ score did capture the sum total of an individual's intellectual ability. He also believed that intelligence was almost 100 percent inheritable and that nothing could be done after birth to alter it.

Based on these beliefs about intelligence, Goddard became a leading figure in the eugenics movement, or the science of controlled breeding of humans. This was in part because Goddard believed that people with lower IQ scores weren't just dumber than others, they were also less moral. That's why many criminals, alcoholics, and prostitutes were morons, Goddard said. But what made his views so dangerous, in Gould's view, are statements like this: "How can there be such a thing as social equality with this wide range of mental capacity?" Goddard asked this question to graduates at Princeton University.

Goddard was thrilled by the then-new discoveries of genetics. In the early 20th century scientists believed that there was a simple one-to-one relationship between a single gene and its physical expression. We now know that isn't true for most traits, which are governed by a complex interaction between multiple genes and the environment. But in 1914 Goddard published a paper in which he asserted that there must be a single dominant gene for normal intelligence along with a single recessive gene for mental deficiency. Goddard claimed that morons carried two copies of the recessive gene. "Dull" people who did manual labor carried only one copy along with one of the dominant intelligence genes.

Therefore, no moron should be allowed to marry or reproduce. This is where Goddard crossed over into eugenics. In order to eradicate the scourge of feeble-mindedness from society, morons should either be sterilized or forced to live in "colonies" like the home Goddard ran in New Jersey. But that was not enough. The United States needed to keep out morons trying to enter the country via immigration. Goddard went to the immigration center at Ellis Island in New York Harbor and tested a boy who scored so low on the Binet scale that Goddard deemed him defective. He dismissed as unimportant the interpreter's concerns that the test was unfair because the boy didn't speak English. Goddard sent women back a year later to do more tests. The results were striking: anywhere from 80 to 87 percent of the immigrants tested as morons. At first Goddard struggled to believe his own figures, but he stood by the results and even called for stricter immigration rules to keep the tide of feeble-minded immigrants safely away from American shores.

By 1928 Goddard's views had softened. He had not changed his hereditarian beliefs that any child born to a moron parent would be a moron as well, but he did not believe that there was any danger of a moron producing idiots or imbeciles, the technical terms used back then by psychologists in to describe adults who were so impaired mentally that they could not function on their own. If a moron had a moron child, at least they could be trained and could work as menial laborers; therefore, Goddard now proclaimed that this was safe for society.

Lewis M. Terman and the Mass Marketing of Innate IQ

From the moment a traveling phrenologist felt the bumps on 10-year-old Lewis M. Terman's head, he was fascinated with intelligence. When he was a professor of psychology at Stanford University, Terman modified the IQ tests, and ever since the test has been known in the United States as the Stanford-Binet test.

Gould charges that the Terman's modification of the test decreased its reliability by ranking creative answers to questions as wrong, thus falsely lowering the IQ score. Gould gives an example of just such a question. The test sets up a situation where an Indian describes a white man as lazy because he "walks sitting down." Then the question asks what the white man is riding to make the Indian say this. The only acceptable answer is bicycle. If the person being tested answers anything else, they will be marked wrong. But there are several other responses that would also be correct, such as a car or truck, a horse, or even a wheelchair. Gould wonders how can a test like this be an accurate indicator of intelligence.

Terman also made other changes to Binet's test. He created a written version of the test that could be administered to hundreds of students at a time and introduced a new scoring system. Whereas Binet's scores were reported as tested age versus chronological age, Terman used a point scale. An average person would score 100—a scale that was universally adopted and is familiar to everyone today.

Just as Goddard had done early in his career, Terman believed in segregation of "morons" and others from society and advocated that they be prevented from having children. He claimed that "The only effective way to deal with the hopelessly feeble-minded is by permanent custodial care." That was part of his drive to modify the Stanford-Binet version of the IQ test so that it could be administered en masse. Terman wrote that this would be of enormous benefit to society because it would bring "tens of thousands of these high-grade defectives under the surveillance and protection of society."

Terman also wanted to use IQ scores as a means of channeling workers to the type of job most appropriate for them. Imagine Terman's chagrin when a group of "hobos" he tested had a mean score of 89—higher than that he had found among firemen, sales clerks, and policemen.

Terman's work was done largely in schools and was able to demonstrate that within that group, children maintain their IQ scores over time. In other words, if a child tests well (or poorly) in first grade, he or she is likely to test well (or poorly) in high school as well. In trying to explain this, he mistakenly assumed that because some low IQs are caused by genetic defects such as Down's Syndrome, all children with low IQs must have some similar genetic defect. Terman specifically rejected the notion that environmental factors such as poverty, a chaotic home life, or poor schooling had any significant influence on low IQs.

Terman went on to predict that IQ testing of nonwhite groups such as Native Americans, Mexicans, and African Americans would reveal "enormously significant racial differences in general intelligence, differences which cannot be wiped out."

These were Terman's assertions in 1916. But in 1937 when he revised the Stanford-Binet test, he backed away from many hereditarian claims such as this. Although he never specifically retracted what he had said about heredity, he remained silent about it and talked much more about environmental causes for differences in IQ between groups. What had changed? Terman himself doesn't say, but Gould ascribes it to changing times. There are fashions in science and psychology just as in popular culture.

R.M. Yerkes and the Army Mental Tests: IQ Comes of Age

Going back to 1915, Gould introduces readers to Robert M. Yerkes, a frustrated psychologist at Harvard University who wanted to elevate the status of his field to that of a "hard" science like physics. Yerkes believed that the way to do this was through numbers, so he embraced IQ testing. But he realized it needed to be standardized, especially in terms of how it was scored. To do this he needed lots and lots of data. With World War I looming, Yerkes was able to persuade the U.S. Army to test all 1.75 million of its recruits. Yerkes later claimed that his testing "helped to win the war." Whether that was true, it certainly helped Yerkes. He made his results public in 1921 and ushered in the era of mass intelligence testing throughout the United States.

Three conclusions Yerkes and his colleagues derived from these numbers continued to affect American social policy for years to come. These conclusions were that the average mental age of white male adults was only 13, just above that of morons, that Europeans from the north of that continent were more intelligent than either Slavs of Eastern Europe or the "darker peoples" of southern Europe, and that black people lie at the bottom of the IQ scale. There were several nonhereditarian explanations for these results. At the time, few Army recruits had the opportunity to attend high school. Many of the recruits were recent immigrants from Europe who did not understand English well. And the black recruits, especially those from the South, were still suffering from the lingering social after-effects of slavery. But Yerkes and his colleagues rejected all those explanations out of hand. They insisted that their results proved the heritability of intelligence.

Gould critiques both the content of the Army Mental Tests and the often slipshod way it was administered in chaotic military training camps. Nevertheless, the statistics derived from these tests were used as support by racists and eugenicists for years afterwards despite the fact that scores for immigrants and African Americans were artificially lowered because they were given the wrong test. There were two different versions of the Army Mental Test: a verbal Alpha test and a pictorial Beta test for those who were illiterate or who did not read English. Because the lines for the Beta test grew so long, impatient officers who didn't support the psychologists in the first place shunted men to the Alpha test instead.

There were numerous other issues with the Beta test, including the fact that it required familiarity with numbers and arithmetic. In addition, the men taking it were never told why they were being tested, while the Alpha subjects were. They were new to the Army and, in some cases, new to the country, and they may have feared that poor performance would results in punishment of some kind. Anyone who has taken a standardized test can empathize with that. Gould includes many parts of the test in the book so readers can try it on themselves. He gave the test to his own Harvard undergraduates and many didn't finish because it was simply impossible to write fast enough to do so. For all these reasons, Gould states that "it is ludicrous to believe that Beta measured any internal state deserving the label intelligence."

The statistical results of the Alpha test should have alerted Yerkes to serious issues with the test itself: too many of the army recruits scored zero. This likely means that the test givers hadn't done a good enough job of explaining the instructions, not that the recruits were too stupid to get even a single question correct.

Yerkes was so ideologically committed to the belief that intelligence was innate that when he was confronted with obvious indications that the men's environment had influenced their test performance, he twisted himself into a pretzel to explain it away. For example, Yerkes found a strong connection between education and test scores: The more years of schooling a recruit had, the better his score on the test. Rather than conclude that his test was measuring education rather than native mental ability, Yerkes contended that "men with more innate intelligence spend more time in school." He further opined that the reason so many African Americans failed to attend school was due to the race's low intelligence. He ignored the fact that schools were segregated in the early 1900s and that black schools were denied the same resources that white schools received. Also, many African Americans were forced to leave school before finishing elementary school in order to work.

Instead of seeing the test results as an indictment of the poor state of education in the United States at that time, people chose to believe that nonwhites and immigrants were born inferior. In the forward to a 1923 book by Princeton University psychology professor C.C. Brigham, Yerkes said just this. He bluntly claimed that the inferiority of these groups was proven fact, not theory. Brigham's book said that society could not "afford to ignore the menace of race deterioration or the evident relations of immigration to national progress."

Brigham brushed off data from Yerkes's tests that did not support his contentions. The appearance of genius in a few Jewish people did not invalidate low test results from recent Jewish immigrants. Additionally, the difference in test performance between African Americans from the segregated South and those from the North wasn't due to better schools. Brigham said it arose because Northern African Americans had more white blood in them—and that smarter African Americans who did live in the South left as soon as they could.

Brigham had the most difficulty defending the notion of hereditarianism when it came to the test scores of immigrants. If intelligence level was inborn and permanent, how could he explain the drop in immigrant IQ scores over time? Brigham came up with a theory that not all immigrants were alike. Those from Nordic countries were smartest, followed by those from the Alpine areas, with those from the Mediterranean basin being the least intelligent. Twenty years earlier more Nordic immigrants arrived in the United States, but now there were more Italians, Greeks, and Slavs. Test scores were lower due to the "change in the races migrating to this country, and to the additional factor of the sending of lower and lower representatives of each race." Thus, Brigham proposed restrictions on immigration from these countries. He also hinted at policies that would prevent "defective strains" in the American-born population— African Americans among them—from reproducing.

The effects of Yerkes's Army Mental Tests went far beyond the military. They helped legitimize IQ testing in the United States as a whole and were also used to promote racial segregation and discrimination. The results of the tests were also used as ammunition in the push to limit immigration and helped lead to the passage of the 1924 Restriction Act. Gould sees this as a victory for the forces of scientific racism. As President Calvin Coolidge said when he signed the bill, "America must be kept American."

Years later Brigham realized that he had made a mistake. He publicly apologized for this, saying he was wrong about the test being able to measure intelligence at all, much less claim that it was some real thing that was inherited. He admitted that the tests were probably measuring knowledge, education, and familiarity with mainstream American culture, not intelligence.

But the damage was done. Gould quotes one expert who estimates that in the years before World War II, six million people from Southern, Central, and Eastern Europe were barred from entering the United States. "We know what happened to many who wished to leave but had nowhere to go," Gould writes, alluding to the six million Jews who perished in the Holocaust: "Ideas can be agents as sure as guns and bombs."


In the title of this chapter, Gould states that the conflation of IQ tests with the belief that intelligence is inherited is a peculiarly American invention. He finds it ironic that this should have happened in a country that prides itself on offering equal opportunity to all. He is clearly upset that scientific data were misused in order to deny opportunities to others. Gould's analysis of the reports of three American psychologists demonstrates conclusively that they were allowing their prejudices to distort their interpretations of intelligence tests. This is yet another argument Gould uses to warn readers that they should not blindly trust statistics. Even if a scientist's name is attached to a report, it is essential to look at the raw data itself. It is also wise to see how the study or experiment was designed and performed. Such background knowledge is essential to evaluate the accuracy and meaning of anything even an expert says.

It is interesting to compare Gould's history of early 20th-century immigration law with current events. During World War I the government passed the 1917 Immigration Act, which required that newcomers to the United States pass a basic reading test and imposed an entry tax. Under this act the only Asian immigrants allowed to enter the United States were from Japan or the Philippines. All other Asian peoples were restricted, including the Chinese who had been excluded by law since 1882.

The Emergency Quota Act was passed in 1921 and added a cap to the number of immigrants who could enter the United States from each country. Under this system immigration was cut by several hundred thousand people per year, mainly affecting those from Eastern and Southern Europe. Reinforced by reports from Yerkes's intelligence testing, race-based fears about white America being overrun by "inferior" groups led to yet another federal act just two years later. The Johnson-Reed Act of 1924 further reduced the number of foreigners allowed to enter the United States and completely banned all immigration from Japan.

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