T
he history of clinical psychology is inextricably
tied to the assessment of intelligence. Without
the success in this and related assessment enterprises,
there might not have been a field of clinical psy-
chology. As the years passed, however, clinicians
became increasingly interested in other aspects of
the profession, such as therapy. Assessment began
to take a back seat, and technicians started to
conduct assessments, as they had prior to World
War II. However, as indicated in earlier chapters,
assessment experienced a renaissance of sorts. Intel-
ligence tests in particular remain prominent in the
clinical psychologist’s arsenal of assessment devices
(Camara, Nathan, & Puente, 2000).
In this chapter, we provide some background
relevant to the controversies over intellectual assess-
ment, present major definitions and theories of intel-
ligence, focus on the measurement of intelligence,
and finally, discuss the appropriate interpretation of
intelligence test scores.
Intelligence Testing: Yesterday and Today
Several important historical developments in the lat-
ter half of the 19th century greatly influenced the
ultimate introduction of measures of intelligence
(Hunt, 2011; Thorndike, 1997; Wasserman &
Tulsky, 2005; White, 2006). First, compulsory edu-
cation in the United States and other countries
resulted in a very diverse student body. Many stu-
dents came from“uneducated”families or families
that did not speak English. As a result, the failure
rate in schools shot up dramatically. To preserve
resources, there was pressure to identify those most
likely to succeed in school. Second, psychological
scientists believed, and ultimately demonstrated,
that mental abilities could be measured. Although
early attempts focused primarily on measures of sen-
sory acuity and reaction time (e.g., Francis Galton,
James McKeen Cattell), the groundwork was laid.
Alfred Binet and his collaborator, Theodore
Simon, became leaders in the intelligence testing
movement when they devised the Binet-Simon
test to identify individual differences in mental func-
tioning (see Chapter 2). Binet’s original purpose was
to develop an objective method of identifying those
truly lacking in academic ability (as opposed to those
with behavior problems). Like others of the day,
Binet and Simon regarded intelligence as a“faculty”
that was inherited, although they also spoke of it as
affected by training and opportunity. With the
interest in quantifying intellectual performance and
with the continuing growth of compulsory educa-
tion in Europe and North America, intelligence
testing became firmly entrenched (Hunt, 2011;
Thorndike, 1997; Wasserman & Tulsky, 2005).
Institutions such as schools, industries, military
forces, and governments were, by their nature,
interested in individual differences (e.g., levels of
intelligence) that might affect performance in
those settings; therefore, intelligence testing pros-
pered. For many years, the critical importance and
F I G U R E 7-1 Alfred Binet developed the first widely
accepted test of intelligence. The test, which eventually
became the Stanford-Binet, has undergone numerous
revisions over the years.
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192 CHAPTER 7