Compare and contrast the Spearman
and Thurston theories of intelligence
500-750+ words. Okay to go over on word count. MLA style.
Please cite any additional sources
IS A WORD FOR WORD QUOTE FROM THE PASSAGE OF TEXT CONCERNING THE PROMPT
Textbook: Hogan, T.P. Psychological
Testing: A Practical Introduction, 3rd
ed., Wiley Publishing Company, 2015
Text reads as follows…
There are two classical theories of intelligence. They have dominated literature on the nature
Charles Spearman (1904, 1927a, 1927b), an Englishman,
developed what is generally considered the first data-based theory about human
Chapter 1 contained a brief description of this
theory. Spearman based this theory. Spearman based his theory on examination of
the correlations between many tests of simple sensory functions. He thought that these correlations were
sufficiently high to conclude that performance on the tests was most dependent
on one general mental ability. He called
this general ability “g” (always
lowercase g). Of course, the correlations
among the various measures were not perfect.
Each test had some unique or specific variance, independent of “g.”
Thus, any set of tests had a series of “s” factors, and one “g” factor. Spearman also relegated error variance to the
“s” factors. Hence, each “s” contained
some variance unique to a specific ability plus error variance. However, many summaries of Spearman’s theory
mention only “g” and “s.”
Figure 7.2 depicts Spearman’s theory. Each oval in the figure represents a
test. The degree of overlap between the
ovals represents the degree of correlation between them. The large area in the center corresponds to “g,”
the general factor in mental ability.
Each oval also has an area that does not overlap with other ovals. The areas of nonoverlap are the “s” factors,
specific to that particular test.
Since the theory has two types of factors (“g” and a
series of “s’s”), Spearman called it two-factor
theory. However, the dominant factor
in the theory is “g.” The “s’s” are not
of much interest. Hence, despite
Spearman’s use of the two-factor terminology, the theory is usually called a
one-factor or unifactor theory of intelligence.
Sometimes it is simply called the theory of “g.”
In the process of developing his theory of human
intelligence, Spearman worked out the elements of factor analysis. We reviewed this statistical technique
earlier (p. 183). By today’s standards,
his methods were quite primitive.
However, he showed remarkable insight regarding how to think about the
relationship among many tests, thus pointing the way for a wide variety of
applications in testing and other social sciences.
Spearman’s “g” remains a central concept in
psychologists’ thinking about intelligence.
It serves as a common reference point in the test manuals, as well as in
other theories about intelligence. We
should note that Spearman’s original works, though now dated in many respects,
provide a rich source of insights for the modern student of psychology. Many contemporary summaries of Spearman’s
work over simplify his thinking. For
example, in addition to “g” is the central concept with the most enduring
influence in the field.
Primary Mental Abilities
Throughout the early years in the debate over the
nature of intelligence, the American psychologist L.L. Thurstone, at the
University of Chicago, provided the main competition to Spearman’s theory of “g.”
Whereas Spearman said that the correlations among different tests were high
enough to think that they were mostly measuring one common factor, Thurston
(1938) believed that the correlations were low enough to think they were measuring
several largely independent factors, thus yielding a multiple-factor theory.
Figure 7.3 depicts Thurstone’s theory.
As in the illustration of Spearman’s theory, the degree of overlap among
the ovals represents the level of correlation.
Thurstone emphasized the separation between ovals, whereas Spearman
emphasized the overlap. Each of the “P’s”
in Figure 7.2 is relatively independent factor.
Like Spearman, in the process of developing his theory, Thurstone made
major contributions to factor-analytic methodology. His books, The Vectors of the Mind
(Thurstone, 1938), and especially its revision, Multiple-Factor Analysis
(Thurstone, 1947), helped define modern factor analysis.
In his most famous study, Thurstone (1938)
administered a battery of 60 tests (15 hours of testing!) to 240 students. (The sample was highly selective: all males
and nearly all students at the University of Chicago.) Thurstone extracted
twelve factors, nine of which he considered interpretable. He called these group factors or primary mental abilities. The latter term stuck. Table 7.2 lists the nine factors originally
identified by Thurstone, with brief descriptions of each factor.
Interestingly, Thurstone was the only major theorist
who authored mental ability tests that attained any widespread use. There were editions from different publishers
and for different age levels. None of the
tests is currently in use.
Understandably, all the tests included the tag “primary mental abilities”
(PMA), which we will use as a generic descriptor here. The various versions of the PMA test covered
only five of the original nine factors—but not always the save five! Thus, there are many references in the
literature to Thurstone’s five factors, but one easily becomes confused tyring
to identify exactly what the five factors are.
As summarized in Table 7.3, of the original nine factors, four factors
appear in nearly all versions of PMA tests: spatial, numerical, verbal, and
reasoning. The original factors
induction, reasoning, and deduction collapse into a single reasoning
factor. The perceptual, memory, and word
fluency factors appear in some PMA tests but not in others, always bringing the
total number of tests to five. Of these
last three factors, the perceptual factor most frequently appeared as the fifth
factor in a PMA test.
Thurstone was not the only person to propose a
multifactor theory of intelligence. In
what he called the structure of intellect
model, J.P. Guilford (1956, 1959b, 1967, 1985, 1988) presented what is
undoubtedly the most extreme version of a multifactor theory of intelligence. According to Guilford, mental ability
manifests itself along three principles axes: contents, products, and
operations. Each of these axes contains
further subdivisions—five for content, six for products, and six for
operations. The three axes may be
depicted in the form of a cube, with the subdivisions forming cells, thus
yielding 5 X 6 X 6 = 180 cells, which Guilford posited to be relatively
independent of one another.
Guilford’s theory has not stood the test of time (and
research). But one of the distinctions
build into the model has endured, that is, the distinction between divergent
production and convergent production. There
were subdivisions along the operations axis.
Divergent production involves
producing alternative or unusual solutions.
involves identification of a single correct answer. That is, in convergent thinking, the mind
converges on one answer. In divergent
thinking, the mind diverges from the usual path to seek diverse possibilities. This reference to divergent thinking helped
stimulate a great deal of research
S Spatial Spatial,
especially visual, ability, as in doing mental rotations of geometric figures
or counting hidden blocks
P Perceptual Perceptual,
especially speed of visual perception, as in scanning a printed page to
identify letters or comparing columns of numbers
N Numerical Numerical,
especially, speed and accuracy of computation
V Verbal Verbal,
including verbal analogies, antonyms, reading comprehension
M Memory Rote,
short-term memory, as in paired-associate learning
W Words Word
fluency, especially dealing with isolated words, as in the disarranged word
test or word fluency test.
I Induction Finding
a rule or principle to solve a problem, as in number series, figure
classification, or pattern analogies
R Reasoning Reasoning,
especially when dealing with a closed-solution problem as in arithmetic
D Deduction A
factor weakly defined by several tests calling for application of a rule.