In 1903 Binet and Theodore Simon (1878–1961) were commissioned by the
French government to develop a test that could identify learning disabled or
mentally retarded children, so that they could be given special education. At
the time, tests based on Galton’s theories were used, but, as discussed before,
some research seemed to discredit Galton’s ideas about the basis of individual
differences. Besides, as Binet noted, children with vision and hearing impair-
ments would be erroneously classified as retarded. Binet proposed instead that
more complex tests of reasoning, motor performance, spatial thinking, and
memory be used to assess a child’s cognitive abilities. Binet and Simon’s tests
included reasoning problems, reflecting Binet’s belief that the intelligent person
was one who showed reasoned judgments when confronted with problems
(Binet, 1911; Binet & Simon, 1916). Typical items on the test required children
to define common words, name objects in pictures, tell how two objects are
alike, draw designs from memory, repeat back a string of spoken digits, and
answer abstract questions such as ‘‘When a person has offended you and comes
to offer his apologies, what should you do?’’
Binet ordered his hodgepodge of tests from simple ones, which most two-
year-old children could answer, to difficult ones, which children could not an-
swer but most adults could answer. The age associated with the most difficult
tasks that the child could perform was designated the child’s mental age, which
was then compared with the child’s chronological age. In 1911 William Stern
(1871–1938) proposed that mental age be divided by chronological age and
then multiplied by 100 to produce the familiar IQ score. Using this formula, if
a 10-year-old child is able to answer most of the items that a typical 12-year-
old could answer, then the 10-year-old child’s IQ score would be (12/10)
100 ¼120. More recently, IQ has been measured by looking at the average for
the age group and determining how far above or below the average the test
taker’s score lies. Average is set as equal to 100; standard deviation (a measure
of dispersion) is usually set as equal to 15. Using this formula, a person who
scores two standard deviations above the average would be assigned an IQ
score of 130.
Binet did not believe that an IQ score was a measure of intelligence, which he
regarded as too complex to capture with a single number. He made it clear that
IQ was not like weight or height, in that IQ does not represent a quality pos-
sessed by a person. Again, Binet believed that his test was good only as a guide
to help identify children who needed special help. Furthermore, Binet did not
believe that scores on IQ tests necessarily represented a genetically based in-
tellectual potential. Rather, he was optimistic that, with special education,
many children who scored low on the IQ test could greatly improve their rea-
soning, memory, and verbal skills. Binet recommended that special education
be tailored to the individual’s needs and aptitudes, that classrooms for special
education be kept small, and that the initial focus be kept on motivation and
work discipline.
Correlates of IQ
Since the early 1900s, a large number of intelligence tests have been developed.
These include the Stanford-Binet (a modification of Binet’s original test), the
Wechsler scales for children (WISC) and adults (WAIS), each of which com-
782 R. Kim Guenther