IQ Test: Where Does It Come From and What Does It Measure?

The most important criterion in diagnosing a child as learning disabled is the IQ test. The aim of an IQ test is to measure the intelligence of a child, which supposedly is an indication of the child’s potential. But where does the test come from and does it really measure potential?

Intelligence testing began in earnest in France, when in 1904 psychologist Alfred Binet was commissioned by the French government to find a method to differentiate between children who were intellectually normal and those who were inferior. The purpose was to put the latter into special schools where they would receive more individual attention. In this way the disruption they caused in the education of intellectually normal children could be avoided.1

Alfred Binet

Alfred Binet

This led to the development of the Binet Scale, also known as the Simon-Binet Scale in recognition of Theophile Simon’s assistance in its development. It constituted a revolutionary approach to the assessment of individual mental ability. However, Binet himself cautioned against misuse of the scale or misunderstanding of its implications. According to Binet, the scale was designed with a single purpose in mind; it was to serve as a guide to identify children in the schools who required special education. Its intention was not to be used as “a general device for ranking all pupils according to mental worth.” Binet also noted that “the scale, properly speaking, does not permit the measure of intelligence, because intellectual qualities are not superposable, and therefore cannot be measured as linear surfaces are measured.”2 Since, according to Binet, intelligence could not be described as a single score, the use of the Intelligence Quotient (IQ) as a definite statement of a child’s intellectual capability would be a serious mistake. In addition, Binet feared that IQ measurement would be used to condemn a child to a permanent “condition” of stupidity, thereby negatively affecting his or her education and livelihood:

Some recent thinkers…[have affirmed] that an individual’s intelligence is a fixed quantity, a quantity that cannot be increased. We must protest and react against this brutal pessimism; we must try to demonstrate that it is founded on nothing.3Binet’s scale had a profound impact on educational development in the United States — and elsewhere. However, the American educators and psychologists who championed and utilized the scale and its revisions failed to heed Binet’s caveats concerning its limitations. Soon intelligence testing assumed an importance and respectability out of proportion to its actual value.

H. H. Goddard, director of research at Vineland Training School in New Jersey, translated Binet’s work into English and advocated a more general application of the Simon-Binet Scale.4 Unlike Binet, Goddard considered intelligence a solitary, fixed and inborn entity that could be measured.5

While Goddard extolled the value and uses of the single IQ score, Lewis M. Terman, who also believed that intelligence was hereditary and fixed, worked on revising theSimon-Binet Scale. His final product, published in 1916 as the Stanford Revision of the Binet-Simon Scale of Intelligence (also known as the Stanford-Binet), became the standard intelligence test in the United States for the next several decades.6 Once American educators had been convinced of the need for universal intelligence testing, and the efficiency it could contribute to school programming, within a few years,

the Simon-Binet Scale, originally designed for identification of children requiring special instructional attention, was transformed into an integral, far-reaching component of the American educational structure. Through Goddard’s and Terman’s efforts the notion that intelligence tests were accurate, scientific, and valuable tools for bringing efficiency to the schools resulted in assigning the IQ score an almost exalted position as a primary, definitive, and permanent representation of the quality of an individual. Hence, intelligence testing became entrenched in the schools over the next several decades.7Few people realize that the tests being used today — of which the IQ test continues to be the most popular — represent the end result of a historical process that has its origins in racial and cultural bigotry. Many of the founding fathers of the modern testing industry — including Goddard, Terman and Carl Brighan (the developer of the Scholastic Aptitude Test) — advocated eugenics.8 Eugenics is a movement concerned with the selective breeding of human beings. Selected human beings would be mated with each other in an attempt to obtain certain traits in their offspring, much the same way that animal breeders work with champion stock. The eventual goal of eugenics is to create a better human race. The Nazis took this idea to the extreme. All “inferior” humans, especially Jews, retarded children or adults, and any individuals with genetic defects, were to be destroyed; and so many ill and retarded people, and many Jews, were killed during World War II.9

The founding fathers of the testing industry saw testing as one way of achieving the eugenicist aims. Goddard’s belief in the innateness and inalterability of intelligence levels, for example, was so firm that he argued for the reconstruction of society along the lines dictated by IQ scores:

If mental level plays anything like the role it seems to, and if in each human being it is the fixed quantity that many believe it is, then it is no useless speculation that tries to see what would happen if society were organized so as to recognize and make use of the doctrine of mental levels… It is quite possible to restate practically all of our social problems in terms of mental level… Testing intelligence is no longer an experiment or of doubted value. It is fast becoming an exact science… Greater efficiency, we are always working for. Can these new facts be used to increase our efficiency? No question! We only await the Human Engineer who will undertake the work.10As a result of his views on intelligence and society, Goddard lobbied for restrictive immigration laws. Upon his “discovery” that all immigrants, except those from Northern Europe, were of “surprisingly low intelligence;” such tight immigration laws were enacted in the 1920s.11 According to Harvard professor Steven Jay Gould in his acclaimed book The Mismeasure of Man, these tests were also influential in legitimizing forced sterilization of allegedly “defective” individuals in some states.12

By the 1920s mass use of the Stanford-Binet Scale and other tests had created a multimillion-dollar testing industry.13 By 1974, according to the Mental Measurements Yearbook, 2,467 tests measuring some form of intellectual ability were in print, 76 of which were identified as strict intelligence tests.14 In one year in the 1980s, teachers gave over 500 million standardized tests to children and adults across the United States.15 In 1989 the American Academy for the Advancement of Science listed the IQ test among the twenty most significant scientific discoveries of the twentieth century along with nuclear fission, DNA, the transistor and flight.16 Patricia Broadfoot’s dictum that “assessment, far more than religion, has become the opiate of the people,”17 has come of age.

So what are we actually measuring?

If an IQ test is supposed to measure a person’s intelligence, the question is: What is intelligence? Is it the ability to do well in school? Is it the ability to read well and spell correctly? Or are the following people intelligent?

  • The physician who smokes three packets of cigarettes a day?
  • The Nobel Prize winner whose marriage and personal life are in ruins?
  • The corporate executive who has ingeniously worked his way to the top and also earned a heart attack for his efforts?
  • The brilliant and successful music composer who handled his money so poorly that he was always running from his creditors (incidentally, his name was Mozart)?18

The problem is that the term intelligence has never been defined adequately and therefore nobody knows what an IQ test is supposed to measure. In spite of this the futures of thousands of children are determined by the results of this test.

Already in the early 1920s the journalist Walter Lippmann maintained that IQ tests were nothing but a series of stunts. “We cannot measure intelligence when we have not defined it,” he said.19

In 1962 Banesh Hoffman told a shocked America about the “tyranny of testing” in his classic book of the same name. His book and others that followed stirred up much controversy, leading the National Education Association in 1976 to recommend the elimination of group standardized intelligence, aptitude, and achievement tests.20 Sarason quotes an advertisement that was placed by Psychology Today in the New York Times in August 1979, part of which appears below:

In the chaos of controversy, the standard IQ exam is flunking the test. Many educational psychologists feel that IQ testers have failed to answer two all-important questions: What is intelligence? What have IQ tests actually measured?The National Education Association, with membership of almost 2 million teachers, has called for the abolition of standardized intelligence tests because they are “at best wasteful, and at worst, destructive.”

Yale psychologist Robert Sternberg says in P.T. that psychologists know “almost nothing about what it is that they have been measuring. The tests have proved overall to have only low to moderate power to predict such things as future job performance, income and status, or overall happiness and adjustment.”21

However, the dust soon settled after this uprising and the testing industry became more powerful than ever. The National Education Association has completely changed its stand and now “recognizes the need for periodic comprehensive testing for evaluation and diagnosis of student progress.”22 This is no wonder, says Dr. Thomas Armstrong, since it would have taken a major miracle to eliminate testing.23

Today, voices for the elimination of standardized tests are few. One is Linda S. Siegel, professor in the Department of Educational Psychology and Special Education at the University of British Columbia in Vancouver, Canada. She proposes that we abandon the IQ test in the analysis of the LD child. According to most definitions — although they are not conclusive — intelligence is made up of the skills of logical reasoning, problem solving, critical thinking, and adaptation.24 This scenario seems reasonable, until one examines the content of IQ tests. The definition of intelligence, as is operationalized in all IQ tests, includes virtually no skills that can be identified in terms of the definitions of intelligence. To support her statement, Siegel gives a detailed analysis of the subtests of the Wechsler Intelligence Scale for Children-Revised (WISC-R). This IQ test is composed of Verbal and Performance sections, and is nearly always used in LD diagnosis. In each subtest of the Verbal scale, performance is in varying degrees dependent on specific knowledge, vocabulary, expressive language and memory skills, while in the Performance scale, visual-spatial abilities, fine motor coordination, perceptual skills, and in some subtests speed, are essential for scoring.25 As Siegel rightly points out, IQ tests measure, for the most part, what a person has learned, not what he or she is capable of doing in the future (his potential).26

There is an additional problem in the use of IQ tests with individuals with learning disabilities. According to Siegel it is a paradox that IQ scores are required of people with LD because most of these persons have deficiencies in one or more of the component skills that are part of these IQ tests — memory, language, fine motor skills, et cetera. The effect is that they may end up having a lower IQ score than a person who does not have such problems, even though they may both have identical reasoning and problem-solving skills. The lower IQ score, therefore, may be a result of the learning disability, and IQ scores may underestimate the real intelligence of the individual with a learning disability.27

Another assumption of the discrepancy definition is that the IQ score should predict reading, so that if you have a low IQ score you should be a poor reader and that poor reading is an expected consequence of low IQ. However, there are individuals who have low IQ scores and are good readers.28

The unreliability of IQ tests has been proved by numerous researchers. The scores may vary by as much as 15 points from one test to another,29 while emotional tension, anxiety, and unfamiliarity with the testing process can greatly affect test performance.30 In addition, Gould described the biasing effect that tester attitudes, qualifications, and instructions can have on testing.31 In one study, for example, ninety-nine school psychologists independently scored an IQ test from identical records, and came up with IQs ranging from 63 to 117 for the same person.32

In another study, Ysseldyke et al. examined the extent to which professionals were able to differentiate learning-disabled students from ordinary low achievers by examining patterns of scores on psychometric measures. Subjects were 65 school psychologists, 38 special-education teachers, and a “naive” group of 21 university students enrolled in programs unrelated to education or psychology. Provided with forms containing information on 41 test or subtest scores (including the WISC-R IQ test) of nine school-identified LD students and nine non-LD students, judges were instructed to indicate which students they believed were learning disabled and which were non-learning disabled.33

The school psychologists and special-education teachers were able to differentiate between LD students and low achievers with only 50 percent accuracy. The naive judges, who had never had more than an introductory course in education or psychology, evidenced a 75 percent hit rate.34 When Ysseldyke and Algozzine cite Scriven, they clearly show their belief that the current system is in trouble:

The pessimist says that a 12 ounce glass containing 6 ounces of drink is half empty — the optimist calls it half full. I can’t say what I think the pessimist could say about research and practice in special education at this point, but I think the optimist could say that we have a wonderful opportunity to start all over!35

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  1. Swiegers, D. J., & Louw, D. A., “Intelligensie,” in D. A. Louw (ed.), Inleiding tot die Psigologie (2nd ed.), (Johannesburg: McGraw Hill, 1982), 145.
  2. Gould, S. J., The Mismeasure of Man (New York: W. W. Norton, 1981), 151-152, cited in Osgood, “Intelligence testing and the field of learning disabilities: A historical and critical perspective,” Learning Disability Quarterly, 1984, vol. 7, 343-348.
  3. Gould, The Mismeasure of Man, 153-154, cited in Osgood, “Intelligence testing.”
  4. Gould, The Mismeasure of Man, 159, cited in Osgood, “Intelligence testing.”
  5. Goddard, H. H., Human Efficiency and Levels of Intelligence (Princeton: Princeton University Press, 1920), 1, cited in Osgood, “Intelligence testing.”
  6. Linden, K. W., & Linden, J. D., Modern Mental Measurement: A Historical Perspective(Boston: Houghton Mifflin, 1968), cited in Osgood, “Intelligence testing.”
  7. Osgood, “Intelligence testing.”
  8. Armstrong, T., In Their Own Way: Discovering and Encouraging Your Child’s Personal Learning Style (Los Angeles: Jeremy P. Tarcher, Inc., 1987), 27.
  9. Dworetzky, J. P., Introduction to Child Development (St. Paul: West Publishing Company, 1981), 82-83.
  10. Goddard, Human Efficiency and Levels of Intelligence, v-vii, cited in Osgood, “Intelligence testing.”
  11. Gould, The Mismeasure of Man, 167, cited in Osgood, “Intelligence testing.”
  12. Gould, The Mismeasure of Man, cited in Armstrong, In Their Own Way, 28.
  13. Osgood, “Intelligence testing.”
  14. Buros, O. K. (ed.), Mental Measurements Yearbook (Highland Park, NJ: Gryphon Press), cited in Osgood, “Intelligence testing.”
  15. Armstrong, In Their Own Way, 27.
  16. Bjorklund, D. F., Children’s Thinking: Development Function and Individual Differences(Pacific Grove, CA: Brookes/Cole, 1989), cited in P. Engelbrecht, S. Kriegler & M. Booysen (eds.), Perspectives on Learning Difficulties (Pretoria: J. L. van Schaik, 1996), 109.
  17. Broadfoot, P., cited in Engelbrecht et al. (eds.), Perspectives on Learning Difficulties, 109.
  18. Dworetzky, Introduction to Child Development, 348.
  19. Lippman, cited in N. J Block & G. Dworkin (eds.), The IQ Controversy: Critical Readings(New York: Pantheon Books, 1976).
  20. Armstrong, In Their Own Way, 26.
  21. New York Times, August 1979, cited in S. B. Sarason, Psychology Misdirected (New York: The Free Press, 1981).
  22. National Education Association Handbook, 1984-85 (Washington, DC: National Education Association of the United States, 1984, 240), cited in Armstrong, In Their Own Way, 27.
  23. Armstrong, In Their Own Way, 27.
  24. Siegel, L. S., “Issues in the definition and diagnosis of learning disabilities: A perspective on Guckenberger v. Boston University,” Journal of Learning Disabilities, 1 July 1999, vol. 32.
  25. Siegel, L. S., “IQ is irrelevant to the definition of learning disabilities,” Journal of Learning Disabilities, 1989, vol. 22(8), 469-478.
  26. Siegel, “Issues in the definition and diagnosis of learning disabilities.”
  27. Ibid; Siegel, “IQ is irrelevant to the definition of learning disabilities.”
  28. Siegel, L. S., & Metsala, E., “An alternative to the food processor approach to subtypes of learning disabilities,” in N. N. Singh & I. L. Beale (eds.), Learning Disabilities: Nature, Theory, and Treatment (New York: Springler-Verlag, 1992), 45.
  29. Smith, C. R., Learning Disabilities: The Interaction of Learner, Task, and Setting(Boston: Allyn and Bacon, 1991), 63.
  30. Tyler, cited in A. Anastasi, (ed.), Testing Problems in Perspective (Washington DC: American Council on Education, 1966).
  31. Gould, The Mismeasure of Man, 199-212, cited in Osgood, “Intelligence testing.”
  32. Cited in J. Sattler, Assessment of Children’s Intelligences and Special Abilities (Boston: Allyn & Bacon, 1982), 60.
  33. Epps, S., Ysseldyke, J. E., & McGue, M., “’I know one when I see one’—Differentiating LD and non-LD students,” Learning Disability Quarterly, 1984, vol. 7, 89-101.
  34. Ysseldyke, J. E., & Algozzine, B., “LD or not LD: That’s not the question!” Journal of Learning Disabilities, 1983, vol. 16(1), 26-27.
  35. Scriven, M., “Comments on Gene Glass,” Paper presented at the Wingspread National Invitational Conference on Public Policy and the Special Education Task of the 1980s, cited in Ysseldyke & Algozzine, “LD or not LD.”