Modern I.Q. Theorists


RANDOM QUOTE: "This brings me to the first point I want to make about what this book is not. I am not advocating a morality based on evolution. I am saying how things have evolved. I am not saying how we humans morally ought to behave. ? Letters" --- Richard Dawkins

        Rather than propose a definition for intelligence, Howard Gardner of Harvard offered a definition for an intelligence. "An intelligence is the ability to solve problems, or to create products, that are valued within one or more cultural settings" (Gardner, 1985, p. x).

Gardner questioned the existence of "g" and wrote the following:

    While I do not question that some individuals may have the potential to excel in more than one sphere, I strongly challenge the notion of large general powers. To my way of thinking, the mind has the potential to deal with several different kinds of content, but an individual's facility with one content has little predictive power about his or her facility with other kinds of content. In other words, genius...is likely to be specific to particular contents: human beings have evolved to exhibit several intelligences and not to draw variously on one flexible intelligence. (Gardner, 1985, p. xi)

Much of his theory is based on work he had accomplished by studying normal individuals whose brains have been injured (Gardner, 1982). Gardner (1985) developed eight criteria for an intelligence:

  • potential isolation by brain damage
  • the existence of idiots savants, prodigies, and other exceptional individuals
  • an identifiable core operation or set of operations
  • a distinctive developmental history, along with a definable set of expert "end-state" performances
  • an evolutionary history and evolutionary plausibility
  • support from experimental psychological tasks
  • support from psychometric findings
  • susceptibility to encoding in a cultural symbol system

According to Gardner the brain supports at least seven different abilities or intelligences. Each of these areas may develop relatively independently of one another. Individuals may have strengths and weaknesses and intelligences can be fashioned and combined in a multiplicity of adaptive ways, each being relatively independent of the others. The seven intelligences are linguistic, musical, logical-mathematical, spatial, bodily-kinesthetic, interpersonal, and intrapersonal (Gardner, 1985).

Gardner's multiple intelligence concept was not new. Truman Kelley (1884-1961) published a book in 1928 entitled Crossroads in the Mind of Man in which he criticized Spearman's model and set the stage for research into "various broad multiple factors central to intelligence" (Weiner & Stewart, 1984, p. 88).

Louis Thurstone (1887-1955) and his students did much of the early work explaining a multiple-factor theory. Zusne (1985) noted that Thurstone was the most eminent psychometrician of his time. Thurstone was much more impressed with the importance of clustering among subtests. With the aid of statistical factor analytic techniques which he devised, and with wide sampling of subtests, Thurstone discovered seven distinct clusters of "Primary Mental Abilities" each of which he believed represented an independent element of the intellect (Fancher, 1985).

Thurstone and his students proposed the following seven factors: induction, applying general reasoning; rote memory, recalling rote material immediately; number, speed and accuracy of arithmetic calculations; perceptual speed, quickness and accuracy at visually noting details; space, perception of spatial relationships; verbal comprehension, understanding word meanings in context; and word fluency, using words in rhyming or categorization (Weiner & Stewart, 1984).

Thurstone worked with his wife Thelma Gwinn Thurstone from 1924 to 1948 developing the Psychological Examinations and the Primary Mental Abilities batteries. He moved to the University of North Carolina at Chapel Hill in 1952 . He died in 1955 and his wife completed some of his funded work at the UNC Psychometics Laboratory (Bashaw & Bashaw, 1990).

As well as disagreeing with Spearman on a general factor of intelligence, Kelley also disagreed with Thurstone on several points of factor analysis. Kelley believed that the value of a given factor should be included in any analysis so the importance of factors be considered. He also felt the total variance of a correlation matrix should be used, rather than just the common variance (Zusne, 1985).

When Thurstone applied his tests and analysis to children a second order "g" factor emerged. Shouksmith (1970) reported that H.E. Garrett used these findings to develop his developmental theory of intelligence. Garrett found that correlations among test involving verbal, numerical and spatial concepts became progressively lower as the age of the sample increased from 8 to 18. He believed that "as a child develops, so his or her abilities differentiate, and the functional generality we find among tests at the younger age level, breaks down into the quasi-independent factors quoted by Thurstone and his followers" (p. 68). Shouksmith reported that the relationship between adults and children was not as simple as Thurstone reported and noted that Anastasi found similar discrepancies when comparing Army recruits and college students.

J. P. Guilford was responsible for "...[p]robably one of the most ambitious attempts to simplify the factors within intelligence" (Weiner and Stewart, 1984, p. 89). Guilford called his work the structure-of-intellect model and represented it by a three dimensional cube. Each dimension represents a way to classifying intelligence. The following is Guilford's (1969) description of the model"

    One basis of classification is according to the basic kind of process or operation performed...[a] second way of classifying the intellectual factors is according to the kind of material or content involved...[w]hen a certain operation is applied to a certain kind of content, as many as six general kinds of products may be involved. There is enough evidence available to suggest that, regardless of the combination of operations and content, the same six kinds of products may be found associated. (p. 100-101)

Guilford's original model combined visual and auditory into a figural content (Weiner & Stewart, 1984). According to Guilford, "intelligence" is too complex to be covered by a few primary mental abilities, much less by a single g-factor value or IQ score (Fancher, 1985).

Through the use of factor analysis, the California psychologist found 120 separate categories which defined the intellectual abilities that make up one's intelligence. Guilford (1977) noted that " . . . [o]rdinary IQ scales assess only a limited number of . . . [one's abilities], usually those most important for learning in school . . . [and one ] may be high in some, medium in others, and low in still others" (p. 13).

Although the concept of multiple intelligence or multiple facets of intelligence is currently popular, there are theorists who support Spearman's "g" factor. The most prominent among them is probably Arthur Jensen who stated the following:

    It is only when the concept of g is attributed meaning above and beyond that derived from the factor analytic procedures from which it gains its strict technical meaning that we run into the needless argument over whether g is a unitary ability or a conglomerate of may subabilities, each of which could be measured independently. We should think of g as a "source" of individual differences in scores which is common to a number of different tests. As the tests change, the nature of g will also change. (p. 11)

Jensen (1980) included Spearman in a list of the three most influential men in the testing movement and although he supported the "g" factor of intelligence he noted that there are "also 'group factors' that are common to groups of items...[and] items may be composed in such a way as to measure g plus one or more group factors" (p. 128).

Jensen believed that the existence of "g" could not be disproved and wrote the following regarding the existence of "g":

    Although psychologists can devise tests that measure only one group factor, they cannot devise a test that excludes g....The ubiquitous common factor to all tests is g, which has been aptly referred to as the primary mental ability....And the same g permeates scholastic achievement and many types of job performance, especially so-called higher-level jobs. Therefore, g is most worthy of our scientific curiosity. (Fancher, 1985, p. 159)

Robert Sternberg introduced a three part theory of intelligence known as the triarchic theory. Sternberg (1985) based his theory on the relationship between intelligence and experience, the external world, and the internal world of the individual.

The relationship with the internal world is academic smart, which is what Sternberg said IQ tests usually measure (Trotter, 1986). This encompasses his componential subtheory involving analytical thinking. Being street smart involves his contextual subtheory. In this, one learns how to manipulate the environment. The third type of intelligence covers the experiential subtheory, which entails being a creative thinker. With this, one is seeing old problems in new way.

Sternberg is currently developing the Sternberg Multidimensional Abilities Test to assess the three intellectual strengths. One can only wonder what future assessment instruments will evolve from this test, or in what ways or in what situations the test will be used for which it was not designed. Once again the mental measurement cycle begins. Many people treat intelligence as if it were a physical substance like hair color or height. One may have "x" amount of it while someone else has "y" amount of it. Dr. Alexander Wesman of the Psychological Corporation wrote:

    We might better remember that it is no more reified than attributes like beauty, or speed, or honesty. There are objects which are classified as beautiful; there are performances which may be characterized as speedy; there are behaviors which display honesty. Each of these is measurable, with greater or less objectivity. Because they can be measured, however, does not mean they are substances. We may agree with E.L. Thorndike that if something exists it can be measured; we need not accept the converse notion that if we can measure something it has existence as a substance. (Winer & Stewart, 1984, p. 87)

    
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