The Bell Curve: Intelligence and Class Structure in American Life (6 page)

In this cloistered environment, the continuing debate about intelligence was conducted much as debates are conducted within any other academic discipline. The public controversy had surfaced some genuine issues, and the competing parties set about trying to resolve them. Controversial
hypotheses were put to the test. Sometimes they were confirmed, sometimes rejected. Often they led to new questions, which were then explored. Substantial progress was made. Many of the issues that created such a public furor in the 1970s were resolved, and the study of cognitive abilities went on to explore new areas.

This is not to say that controversy has ended, only that the controversy within the professional intelligence testing community is much different from that outside it. The issues that seem most salient in articles in the popular press (Isn’t intelligence determined mostly by environment? Aren’t the tests useless because they’re biased?) are not major topics of debate within the profession. On many of the publicly discussed questions, a scholarly consensus has been reached.
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Rather, the contending parties within the professional community divide along other lines. By the early 1990s, they could be roughly divided into three factions for our purposes: the classicists, the revisionists, and the radicals.

The classicists work within the tradition begun by Spearman, seeking to identify the components of intelligence much as physicists seek to identify the structure of the atom. As of the 1990s, the classicists are for practical purposes unanimous in accepting that
g
sits at the center of the structure in a dominating position—not just as an artifact of statistical manipulation but as an expression of a core human mental ability much like the ability Spearman identified at the turn of the century. In their view,
g
is one of the most thoroughly demonstrated entities in the behavioral sciences and one of the most powerful for understanding socially significant human variation.

The classicists took a long time to reach this level of consensus. The ink on Spearman’s first article on the topic in 1904 was barely dry before others were arguing that intellectual ability could not be adequately captured by
g
or by any other unitary quantity—and understandably so, for common sense rebels against the idea that something so important about people as their intellects can be captured even roughly by variations in a single quantity. Many of the famous names in the history of psychometrics challenged the reality of
g,
starting with Galton’s most eminent early disciple, Karl Pearson, and continuing with many other creative and influential psychometricians.

In diverse ways, they sought the grail of a set of primary and mutually independent mental abilities. For Spearman, there was just one such
primary ability,
g.
For Raymond Cattell, there are two kinds of
g,
crystallized
and
fluid,
with crystallized
g
being general intelligence transformed into the skills of one’s own culture, and fluid
g
being the all-purpose intellectual capacity from which the crystallized skills are formed. In Louis Thurstone’s theory of intelligence, there are a half-dozen or so
primary mental abilities,
such as verbal, quantitative, spatial, and the like. In Philip Vernon’s theory, intellectual capacities are arranged in a hierarchy with
g
at its apex; in Joy Guilford’s, the structure of intellect is refined into 120 or more intellectual components. The theoretical alternatives to unitary, general intelligence have come in many sizes, shapes, and degrees of plausibility.

Many of these efforts proved to have lasting value. For example, Cattell’s distinction between fluid and crystallized intelligence remains a useful conceptual contrast, just as other work has done much to clarify what lies in the domain of specific abilities that
g
cannot account for. But no one has been able to devise a set of tests that do not reveal a large general factor of intellectual ability—in other words, something very like Spearman’s
g.
Furthermore, the classicists point out, the best standardized tests, such as a modern IQ test, do a reasonably good job of measuring
g.
When properly administered, the tests are not measurably biased against socioeconomic, ethnic, or racial subgroups. They predict a wide variety of socially important outcomes.

This is not the same as saying that the classicists are satisfied with their understanding of intelligence,
g
is a statistical entity, and current research is probing the underlying neurologic basis for it. Arthur Jensen, the archetypal classicist, has been active in this effort for the last decade, returning to Galton’s intuition that performance on elementary cognitive tasks, such as reaction time in recognizing simple patterns of lights and shapes, provides an entry point into understanding the physiology of
g.

A theory of intelligence need not be structural. The emphasis may be on process rather than on structure. In other words, it may try to figure out what a person is
doing
when exercising his or her intelligence, rather than what elements of intelligence are put together. The great Swiss psychologist, Jean Piaget, started his career in Alfred Binet’s laboratory trying to adapt Cyril Burt’s intelligence tests for Parisian children. Piaget
discovered quickly that he was less interested in how well the children did than in what errors they made.
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Errors revealed what the underlying processes of thought must have been, Piaget believed. It was the processes of intelligence that fascinated him during his long and illustrious career, which led in time to his theory of the stages of cognitive development.

Starting in the 1960s, research on human cognition became the preoccupation of experimental psychologists, displacing the animal learning experiments of the earlier period. It was inevitable that the new experimentalists would turn to the study of human intelligence in natural settings. John B. Carroll and Earl B. Hunt led the way from the cognition laboratory to the study of human intelligence in everyday life. Today Yale psychologist Robert Sternberg is among the leaders of this development.

The revisionists share much with the classicists. They accept that a general mental ability much like Spearman’s
g
has to be incorporated into any theory of the structure of intelligence, although they would not agree that it accounts for as much of the intellectual variation among people as many classicists claim. They use many of the same statistical tools as the classicists and are prepared to subject their work to the same standards of rigor. Where they differ with the classicists, however, is their attitude toward intellectual structure and the tests used to measure it.

Yes, the revisionists argue, human intelligence has a structure, but is it worth investing all that effort in discovering what it is? The preoccupation with structure has engendered preoccupation with summary scores, the revisionists say. That, after all, is what an IQ score represents: a composite of scores that individually measure quite distinct intellectual processes. “Of course,” Sternberg writes, “a tester can always average over multiple scores. But are such averages revealing, or do they camouflage more than they reveal? If a person is a wonderful visualizer but can barely compose a sentence, and another person can write glowing prose but cannot begin to visualize the simplest spatial images, what do you really learn about these two people if they are reported to have the same IQ?”
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By focusing on processes, the revisionists argue, they are working richer veins than are those who search for static structure. What really counts about intelligence are the ways in which people process the information they receive. What problem-solving mechanisms do they employ?
How do they trade off speed and accuracy? How do they combine different problem-solving resources into a strategy? Sternberg has fashioned his own thinking on this topic into what he calls a “triarchy of intelligence,” or “three aspects of human information processing,”
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The first part of Sternberg’s triarchy attempts to describe the internal architecture of intellectual functioning, the means by which humans translate sensory inputs into mental representations, allocate mental resources, infer conclusions from raw material, and acquire skills. This architectural component of Sternberg’s theory bears a family resemblance to the classicists’ view of the dimensions of intelligence, but it emphasizes process over structure.

The second part of the triarchic theory addresses the role of intelligence in routinizing performance, starting with completely novel tasks that test a person’s insightfulness, flexibility, and creativity, and eventually converting them to routine tasks that can be done without conscious thought. Understand this process, Sternberg argues, and we have leverage not just for measuring intelligence but for improving it.

The third part of Sternberg’s triarchy attacks the question that has been central to the controversy over intelligence tests: the relationship of intelligence to the real world in which people function. In Sternberg’s view, people function by means of three mechanisms:
adaptation
(roughly, trying to make the best of the situation),
shaping
the external environment so that it conforms more closely to the desired state of affairs, or
selecting
a new environment altogether. Sternberg laments the inadequacies of traditional intelligence tests in capturing this real-world aspect of intelligence and seeks to develop tests that will do so—and, in addition, lead to techniques for teaching people to raise their intelligence.

Walter Lippmann’s hostility toward intelligence testing was grounded in his belief that this most important of all human qualities was too diverse, too complex, too changeable, too dependent on cultural context, and, above all, too subjective to be measured by answers to a mere list of test questions. Intelligence seemed to him, as it does to many other thoughtful people who are not themselves expert in testing, more like beauty or justice than height or weight. Before something can be measured, it must be defined, this argument goes.
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And the problems of definition
for beauty, justice, or intelligence are insuperable. To people who hold these views, the claims of the intelligence testers seem naive at best and vicious at worst. These views, which are generally advanced primarily by nonspecialists, have found an influential spokesman from the academy, which is mainly why we include them here. We refer here to the theory of multiple intelligences formulated by Howard Gardner, a Harvard psychologist.

Gardner’s general definition of intelligent behavior does not seem radical at all. For Gardner, as for many other thinkers on intelligence, the notion of problem solving is central. “A human intellectual competence must entail a set of skills of problem solving,” he writes, “enabling the individual to
resolve genuine problems or difficulties
that he or she encounters and, when appropriate, to create an effective product—and also must entail the potential for
finding or creating problems—
thereby laying the groundwork for the acquisition of new knowledge.”
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Gardner’s view is radical (a word he uses himself to describe his theory) in that he rejects, virtually without qualification, the notion of a general intelligence factor, which is to say that he denies
g.
Instead, he argues the case for seven distinct intelligences: linguistic, musical, logical-mathematical, spatial, bodily-kinesthetic, and two forms of “personal intelligence,” the intrapersonal and the interpersonal, each based on its own unique computational capacity.
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Gardner rejects the criticism that he has merely redefined the word
intelligence
by broadening it to include what may more properly be called talents: “I place no particular premium on the word
intelligence,
but I do place great importance on the equivalence of various human faculties,” he writes. “If critics [of his theory] were willing to label language and logical thinking as talents as well, and to remove these from the pedestal they currently occupy, then I would be happy to speak of multiple talents.”
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Gardner’s approach is also radical in that he does not defend his theory with quantitative data. He draws on findings from anthropology to zoology in his narrative, but, in a field that has been intensely quantitative since its inception, Gardner’s work is uniquely devoid of psychometric or other quantitative evidence. He dismisses factor analysis: “[G]iven the same set of data, it is possible, using one set of factoranalytic procedures, to come up with a picture that supports the idea of a ‘g’ factor; using another equally valid method of statistical analysis, it is possible to support the notion of a family of relatively discrete mental abilities.”
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He is untroubled by the fact that tests of the varying intelligences
in his theory seem to be intercorrelated: “I fear… that I cannot accept these correlations at face value. Nearly all current tests are so devised that they call principally upon linguistic and logical facility. … Accordingly, individuals with these skills are likely to do well even in tests of musical or spatial abilities, while those who are not especially facile linguistically and logically are likely to be impaled on such standardized tests.”
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And in general, he invites his readers to disregard the thorny complexities of the classical and revisionist approaches: “When it comes to the interpretation of intelligence testing, we are faced with an issue of taste or preference rather than one on which scientific closure is likely to be reached.”
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