Running Head: THE JOURNEY OF THE INTELLIGENCE TEST 1
The Journey of the Intelligence Test
Elizabeth Porter
Brigham Young University-Idaho
Abstract
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Intelligence is an entity that is difficult to define and nearly impossible to measure. However, the
incredibility of the task has not kept psychologists from trying to create a test that can provide an
adequate indication of mental ability. There are deeper contributions behind Galton’s eugenics
and failed physical tests. Binet and Simon’s progress in creating valid mental tests would impact
testing developments for years to come. The ideas of Spearman’s fixed general intelligence
altered the definition of intelligence and revolutionized the movement of measuring it.
Goddard’s contributions planted the intelligence test in a place where its use would increase
exponentially. After standardized testing was introduced through Terman’s Stanford-Binet and
the military’s Alpha Beta tests, methods began to be adapted and revised, continuing to refine the
process of defining the mystery of human wisdom. This research will explore the significance of
those contributions. Understanding these movements is important to comprehending why
humankind is so interested in the idea of intelligence.
Some of the biggest questions that psychology tries to solve are related to that intangible
something that motivates our actions and creates our personalities. There is an unknown factor
that makes unique individuals out of a species of biologically similar creatures. The debates have
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raged: nature versus nurture, mind versus body, and man versus machine. These controversies
have revolved around the power of the functioning human brain, something we call intelligence.
Through analyzing the evolution of defining and measuring intelligence, we can explore the
progressive methods of different psychologists and come to recognize reasons why man feels a
need to specify the faculty of the mind.
Intelligence is an enigmatic entity that has contributed to humankind’s natural tendency
to conform into social hierarchies. The structure of families, occupations, churches, and
governments all include positions of superiority and inferiority. If psychology could define and
explicate such distinctions, perhaps humanity could more clearly understand, and in some cases
justify, the different treatment of these classes. Because a greater understanding of intelligence
has led to justification of mistreatment, measuring intelligence is a controversial issue. Tests
provide a useful, adaptable, and straightforward tool for analyzing people’s strengths and
weaknesses, but can intelligence be that simplified? Because of the ambiguity in the definition of
intelligence and the power of its consequences, the methods of quantifying intelligence have
gone through multiple movements headed by significant psychologists. Phases have ignited and
faded, each influencing the intelligence test in a dramatic way.
With his ideas of evolution, Charles Darwin initiated one of the greatest paradigm shifts
that has occurred in science. His ideas of natural selection gave a new meaning to humankind’s
hierarchical nature. The concept that only the fittest survived elicited the question, “Who are the
fittest?” Social hierarchy provides evident distinctions, and it is easy to assume that those
distinctions are indicative of evolutionary value. To address the validity of this assumption,
scientists set out to discover what factor made those of higher social standing superior to the rest
of the population. It seemed to be something more than physical advantages. They asked, “Is
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there such a thing as psychological fitness?” In an effort to answer, researchers turned to
intelligence testing.
Darwin’s cousin, Sir Francis Galton, was the first of these researchers. His reasoning
supported the idea that social class indicated mental fitness because he believed that the same
genes that determined social status also determined intelligence. Stephen Murdoch (2007),
author of IQ: A Smart History of a Failed Idea, discussed Galton’s reasoning, “Along with the
belief that mental ability is inherited often comes the conclusion that society is structured the
way it is for natural reasons, and so it was for Galton” (p. 14). He concluded that those who
were privileged by society were privileged for their worthier intellectual ability and those who
were underprivileged were innately less intelligent. Galton didn’t want to wait for generations to
pass before natural selection started eliminating the less intelligent genes from society, so he
proposed a notion called eugenics. Murdoch described eugenics as a practice in which the
government arranged the marriages of the upperclassmen and controlled births of underclassmen
(Murdoch, 2007, pp. 14-21). Murdoch further explained that by allowing only the members of
the upperclass to reproduce, the government could ensure that the genes perpetuated to the next
generation were of the best evolutionary value.
To implement his practice, Galton had to have a way to differentiate between those
whose intelligence was worth preserving and those whose intelligence was not. He turned to
testing. He assumed that psychological ability could be measured in a way similar to methods
used to measure physical ability. “To Galton, applying theories about physical attributes . . . to
psychological ones in humans made perfect sense” (Murdoch, 2007, p. 12). Galton immediately
went about creating a system of physical exercises that he hoped would correspond with
intelligence. His product, the Anthropometric Laboratory (Murdoch, 2007, p. 17), stands as the
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first mental test. Murdoch (2007) describes the popularity of Galton’s first attempt to start
collecting data. He purchased a booth at the London Internal Health Exhibition in 1884 and
began attracting intrigued and willing participants immediately (p. 17).
Although the Anthropometric Laboratory did not lack volunteers, Galton found it
impossible to find a correlation between the participants’ scores and their intelligence (Murdoch,
2007, pp. 23-24) To his dismay, Galton’s methods of measuring physical abilities did not
produce results that were solid enough to incite an active practice of eugenics. Despite his sense
of failure, Galton’s methods of numerical measurement gave intelligence testing the scientific
basis it needed to grow. Murdoch (2007) argues that, “Galton’s greatest contribution [to science]
was statistics.” (p. 22). Galton’s method of calculation would be used by later psychologists to
keep the goal of developing an intelligence test alive until it could be eventually adopted by
someone who would find success (pp. 25-28).
Alfred Binet was a frenchman who had studied the tests of Galton and his successors.
Plucker (2007) indicates that while pondering their approaches of physical measurement, Binet
observed that his young daughters’ physical abilities were no less than his own, despite the
obvious difference in mental capacity. Binet realized that the previous scientists’ focus on
physical tasks was what had led to their failure. (Murdoch, 2007, p. 31) Binet concluded, “To
judge well, to comprehend well, to reason well, these are the essential activities of intelligence.”
(Binet, 1905, p. 43) Binet’s emphasis on these mental faculties narrowed the definition of
intelligence. Binet and his assistant, Theodore Simon, conducted a substantial amount of
research on this more specific “fundamental faculty” (Binet, 1905, p. 42) of the mind.
Then,
in 1904, a new french law gave all children an opportunity to go to school (Binet, 1905, p. 9). As
children of all levels of learning flooded into the schoolhouses, France school districts sought a
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way to determine which students needed special education. In his book, The Development of
Intelligence in Children, Binet (1905) explained that he and Simon were hired to solve that need.
They used their research to develop a test which could measure the students’ different levels of
mental capacities (pp. 9-11). His methods were directed toward diagnosing those who problem
solving ability was “subnormal” (Binet, 1904, p. 71). He categorized these students by their
mental age--an indication of where they were intellectually in a child’s typical progression. He
assigned these specific numbers only so that they could receive assistance catered to their needs.
Binet (1905) explained that the theory behind gradually increasing the level of difficulty of the
questions ensured that when a child was no longer able to answer correctly, they had reached the
limit of their reasoning ability (p. 72-73). Binet also made his test brief to eliminate unrelated
factors that could influence performance like attention or focus (p. 254). The result was an
intelligence test that had valid correlation.
Even though his test was a success, Binet (1905) washed his hands clean of defining
intelligence when he said, “We have not attempted to treat, in all its scope, this problem of
fearful complexity, the definition of intelligence.” (p. 253) Binet knew that intelligence was
something deeper and more intricate then his test could measure. He also knew that people
would try to encapsulate the whole potential of a person’s intellect in their test score because of
ease of finally having intelligence so specifically defined. He feared that his intelligence test
would be stretched beyond its bounds. He warned, “In spite of the interest of this classification, it
cannot serve as a faithful guide for study during the life of the patent.” (1905, p. 19) Regardless
of his disclaimer, however, his test would be taken, adapted, and in many cases, misapplied.
While Binet refused to arbitrarily encase intelligence, one of his contemporaries was
striving to do that exact thing. In 1904, Englishman Charles Spearman published an essay about
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an entity called “General Intelligence” (p. 272). In his essay, Spearman (1904) sought a way to
quantify and compare different elements of intelligence, “We now are in need of such a
procedure . . . [that] will focus [our information] in to a plain quantitative value; for the moment,
psychology has to give way to mathematics” (p. 252). With mathematical computation,
Spearman compared students’ scholastic performance to the exactness of their sensory
perceptions.
He revisited Galton’s idea that physical abilities related to psychological abilities, but
unlike Galton, Spearman was able to find correlation by squaring his numerical results. He called
his deductions “factor analysis” (Bower, 2003, p. 92). With factor analysis, Spearman (1904)
made this substantial conclusion:
On the whole, then, we reach the profoundly important conclusion that there really exists
a something that we may provisionally term “General Sensory Discrimination” and
similarly a “General Intelligence” and further that the functional correspondence between
these two is not appreciably less than absolute. (p. 272)
Spearman called his concept the “Theorem of Intellective Unity.” (1904, p. 274) The
correlations he found led him to believe that there was some kind of “substance” (Spearman,
1904, p. 258) that could be specified as “intelligence”. Further, he proposed that intelligence was
a single faculty that was demonstrated consistently across all areas of a person’s life. Therefore,
a person’s ability to perform any kind of task could be inferred by determining their general
intelligence. As may be predicted, this concept of a single all-encompassing intelligence made it
easy to condemn and confine individuals by their amount of general intelligence. For the same
reason that Binet feared people would put to much value in a test score, people embraced
Spearman’s simplicity of an all encompassing element of intelligence.
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This easy solution looked especially attractive to Henry Goddard, a psychologist caught
up in the American movement of reforming mental institutions. Goddard had been hired to study
the patients at the Vineland Training School for Feeble-Minded Boys and Girls (Fletcher &
Hattie, 2011, p.19). His experience there led him to agree with Spearman’s theory that
intelligence was a fixed factor that determined all of one’s capabilities. The nature of the
challenges of the patients at Vineland were more physical in nature, yet Goddard’s efforts at
using physical examinations to understand their mental illnesses had led nowhere (Murdoch,
2007, pp. 40-45). When Goddard translated Binet’s psychological examinations into English,
however, he had correlative data with which he could make meaningful deductions.
Goddard’s first conclusion was that the intelligence level of the feebleminded could not
be altered or improved. After seeing a mother and a daughter both institutionalized at Vineland,
Goddard began to wonder if feeblemindedness was genetic (Fletcher & Hattie, 2011, p. 19). He
studied their family, to whom he gave the pseudonym of Kallikak, and found multiple evidences
of what he considered to be lesser intelligence. His proofs lack validity when viewed through
lenses of modern psychology, but to early 1900s scientists, the correlations were undeniable.
Fletcher & Hattie (2011), authors of Intelligence and Intelligence Testing, explained that
Goddard became concerned that if allowed to reproduce, the mentally ill would only produce
more mentally ill who would be a great burden to society. Goddard’s conclusions led him to
drastic ends:
Goddard . . . espoused views that children with such classifications [of feeblemindedness]
should be segregated from society and even sterilised [sic]. . . . Such was the concern that
33 states . . . passed laws permitting the sterilisation of ‘feeble-minded’ individuals, and
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more than 60,000 men and women housed in mental institutions were sterilised, with
many not knowing what was happening to them. (Fletcher & Hattie, 2011, p. 19)
Although Goddard’s use of the intelligence test to promote eugenics is dark spot in American
history, it cannot be denied that, “Henry Herbert Goddard found and translated Alfred Binet’s
tests at the right historical moment--just in time to capitalize on this fear of the feebleminded.”
(Murdoch, 2007, p. 47). During the institutional reform, physicians felt pressure to understand
the mysterious nature of mental illness. It was the perfect environment for Goddard’s tests to
serve as a “trojan horse” (Murdoch, 2007, p. 46) and grant psychological solutions more reign
and acceptance in the United States.
This new acceptance was capitalized upon by American psychologists, especially after
the United States joined World War I. Murdoch (2007) explains that in an effort to protect the
army from those who were mentally incompetent, psychologists decided to use intelligence
testing to measure recruits. Disputations arose, however, when they began debating the
appropriate method for such large amounts of men. Lewis Terman silenced the argument by
creating a simpler version of the Binet-Simon that could be taken by a classroom full of
participants with pen and paper (p. 86-89). The army adapted Terman’s test to develop the Alpha
and Beta exams. The Alpha test used pictures to ask questions that addressed issues of common
sense. The Beta test strove to address the same issues with words (Fletcher & Hattie, 2011,
p. 22). The design was that implementing both tests would allow english and non-english
speakers to be tested with equal accuracy. The effectiveness of this objective was dubious,
however. Strictly according to the results of the Alpha and Beta tests, “47 percent of white and
89 percent of black servicemen . . . would be technically classified as morons.” (Murdoch, 2007,
p. 87) The army eventually lowered the passing point of their tests to a mental age of eight. Yet,
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in the field, servicemen provided ample evidence that they were much more intelligent than their
scores suggested. The military kept administering the tests, but after seeing the obvious
discrepancy between the scores and the actual reasoning of the soldiers, they did not rely on
them. The inaccuracies did not keep the citizens at home from embracing the IQ, however. The
Alpha Beta tests may not have done much for the military, but they popularized the idea of
psychological measurement in an unprecedented way.
The Alpha Beta and the test it was derived from, Terman’s Stanford-Binet, were
significantly influential because they were standardized tests. They replaced the inconsistencies
and biases of individualized testing with reliability, uniformity, and comparability. These
advantages were made evident, even to common people who had no knowledge of the test’s
history, because of the introduction of the IQ (Intelligence Quotient). Murdoch describes the
test’s revolutionary value, “Terman’s exam would quickly become the gold standard in
intelligence testing and include the now-famous Intelligence Quotient” (2007, p. 73) Terman’s
IQ involved a numerical formula that turned Binet’s concept of mental age into an easily
computable and comprehendible whole number (Fletcher & Hattie, 2011, p. 21). Suddenly, the
common man had the ability to take a test and receive a number quantifying his intelligence. The
IQ test’s simple and accessible nature perpetuated the popularity of Terman’s definition of
intelligence. Jensen (1981), author of Straight Talk About Mental Tests, showed why Americans
became enthralled, “It is people’s perception of the fact that IQ tests can measure this general
factor with reasonable accuracy that arouses their fascination with and anxiety about the IQ.” (p.
11) They believed they had discovered the way to measure the mental muscle, and the idea
spread across the globe.
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During this era, several different countries further developed Terman’s IQ and extended
the use of the intelligence test. Murdoch (2007) describes these movements in IQ: A Smart
History of a Failed Idea. During the reign of Hitler in Germany, the intelligence test provided
perfect grounds on which the Nazi supremacists could decide who was and was not fit to
perpetuate the Aryan race (p. 119-138). In the United States, psychological testing became a part
of American family life through public education as the use of intelligence testing was extended
to solve the problem of overpopulated schools (p. 91). In the late 1950s, a man named Cyril Burt
promoted ideas that led to the development of the eleven-plus test in the United Kingdom
(pp.139-158). The eleven-plus test was a standardized test administered to eleven year olds that,
“decided, in one day, the majority of children’s educational and professional options upon
leaving school” (p. 142). Since then, the Standford-Binet has undergone revisions in 1937, 1960,
1972, 1986, and 2003 (Becker, 2003, p. 4). Methods have varied, but the goal of gaining a more
complete understanding and of establishing a more accurate interpretation of intelligence has
remained the motivation of the movement.
Psychologists haven’t only been busy with refining initial methods, however. Many new
mental tests have sprung up. One of the more enduring of these tests is the Wechsler Adult
Intelligence Scale (WAIS), described in Sternberg’s (2000) The Handbook of Intelligence. The
WAIS has also undergone multiple revisions. It was created by David Wechsler to incorporate
Binet’s emphasis on problem solving questions, Spearman’s idea of mental age, and the army’s
desire to diminish a language barrier. His method also added indications of the test taker’s
strengths and weaknesses (pp. 456-457). Each new test improves the ability of the intelligence
test to accomplish what it was initially developed to achieve.
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The history of the intelligence test has involved many psychologists who have
experimented to explain the nature of mental ability. Through all its different phases of
development--Galton’s failures and Binet’s successes, Goddard’s misuse and the military’s
irrelevant use, Spearman’s mathematical equations and Terman’s conceptions--the intelligence
test has grown to satisfy many of the questions humankind has had as to the enigma of
intelligence.
References
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Bower, B. (2003). Essence of g. Science news, 163, 6, 92-93.
Davidson, C. N., (2011, September 29). A Model T test in the internet age. Retrieved from
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Flynn, J.R. (2003). “Movies about intelligence: The limitations of g.” Current Directions in
Psychological Science, 12, 95-99.
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Jensen, A.R. (1981). Straight talk about mental tests. New York, NY: The Free Press.
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Plucker, J. (2007, July 25). Charles Spearman. Retrieved from
http://www.indiana.edu/~intell/spearman.shtml
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