The Story of Psychology (46 page)

Beta, for illiterate subjects, in the choice of pictures to be completed was similarly unfair, as already mentioned.

The result was to give a distorted assessment of the population and the effects on it of immigration. The Army Testing Program, as presented by Yerkes in his 1921 report, portrayed a society whose population was being degraded by increases in poor genetic stock. According to the Alpha and Beta, the average mental age of white American males was only thirteen, just above the level of moronity, although Terman had previously put the figure at sixteen. Gould said that this shocking datum lent power to xenophobic, racist, and elitist elements in America:

Yerkes also lent support to Goddard’s Ellis Island data by reporting that the Alpha and Beta showed the peoples of southern Europe and the Slavs of eastern Europe to be less intelligent than the peoples of northern and western Europe; these “findings” helped bring about the 1924 immigration law.

As the IQ controversy grew more heated, however, intelligence testing began to lose favor among psychologists during the 1930s and still more in the 1940s. By then, too, the belief in general intelligence had waned; new research using advanced statistical methods had found all sorts of “factors” or clusters of special correlations among the traits and cast doubts on the meaningfulness or usefulness of Spearman’s
g.
Still, tests measuring a number of mental abilities and yielding a composite score, called intelligence, continued to be used by educators, business heads, and others.

By the 1960s, however, with protest movements of the disenfranchised and the discriminated-against gaining power, a protracted IQ war got under way. According to a study the author of this book made in 1999:

Some psychologists went so far as to deny that there was such a thing as intelligence. Professor Martin Deutsch of New York University asserted, “It’s a convenient label for certain kinds of behavior, but I suspect that, in actual fact, the thing itself doesn’t really exist.” Other psychologists and educators preferred to state, as Boring had done earlier, that one cannot say what intelligence is but only that it is what intelligence tests measure.

To meet the criticisms of existing IQ tests, in 1958 the psychologist David Wechsler developed two new ones, the Wechsler Intelligence Scale for Children (known as WISC) and the Wechsler Adult Intelligence Scale (WAIS). WISC and WAIS have two major parts: a verbal subtest assesses vocabulary, comprehension, and other aspects of verbal ability, and a performance subtest is made up of nonverbal tasks such as arranging pictures in an order that tells a story, or spotting the missing elements in a picture. Over the years intelligence researchers have modified and improved them as well as the Stanford-Binet Intelligence Scale to better measure the abilities of test takers from diverse cultural and linguistic backgrounds, and have developed more sophisticated and fairer ways of administering and interpreting the tests.
⁶⁰

Accordingly, despite the long history of opposition to intelligence tests, WISC and WAIS have continued to be widely used in their latest versions (WISC III and WAIS III), and for good reason.

For one thing, in those school systems that use them they predict rather well how children will perform in school and which children should be given special attention or be enrolled in enrichment programs.

For another, a number of recent, statistically sophisticated studies of fraternal twins and identical twins, particularly pairs who were separated shortly after birth and reared in dissimilar homes, have established, far better than Galton could, that mental abilities are in considerable part due to genetic makeup, and therefore that intelligence testing does indeed test innate ability as well as acquired knowledge.
⁶¹

This graph clearly shows the two influences of genetics and environment on IQ.

FIGURE 1
IQ and genetic relationship

Each bar shows how closely the IQ scores of the individuals listed are related. For instance, the top bar indicates that if identical twins are reared together—genetics and environment being the same—their IQs will have a greater than 0.8 correlation (or in informal terms, are very likely to be the same or nearly so.) In contrast, the bar for siblings reared apart—with only half the same genes and different environments— shows that their IQs are likely to be rather different.

(Data of this kind are often mislabeled “heritability,” which is a quite different matter. Heritability refers to how much of the range of differences in a given trait, within a group of people, results from genetics. If the heritability of intelligence were found to be zero, no part of the range from nearly zero to 200 would be of genetic origin; if it were 100 percent, all of the variance would be of genetic origin. Recent reviews of a variety of studies of heritability of IQ conclude that roughly half of the variance in IQ scores is due to genetic makeup.
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But how genetic makeup interacts with culture and which contributes how much of the result in any individual is a complex issue, only now being studied in new and illuminating ways—an area of contemporary psychology that we will see more of later in this history.)

One reason test designers have had to keep tinkering with the IQ tests
is bizarre: in Western society, IQ scores have risen about three points every decade. The average IQ today would be 115 if the tests were scored as they were 50 years ago. To correct for this, scoring methods are periodically adjusted to keep the mean at 100.
⁶³
Several explanations of the improving average scores have been offered: one, that daily life has become more challenging and thereby increased people’s coping ability; two, that nutrition is better and has increased height—and, possibly, brain functioning; and three, that perhaps there has been no real increase in IQ but only in the kind of reasoning ability that is useful in test taking. At present, the definite explanation for rising IQ scores is not known.
⁶⁴

A more serious challenge to the status of IQ tests is the development of more complex portrayals of intelligence. Rather than the summary entity
g
, a number of theories have been offered in recent years that distinguish among kinds of intelligence. The two that currently command the most attention are those of Robert Sternberg of Yale and Howard Gardner of Harvard. Sternberg distinguishes between analytical intelligence (such as one uses in solving anagrams), creative intelligence (called upon in problem solving), and practical intelligence (used in the management of everyday affairs).
⁶⁵
Gardner’s view is more complex: He identifies (and offers evidence for) eight intelligences, some of which are promoted by Western society, others by other societies.
⁶⁶
Here—and we will spare ourselves the details—are his eight:

His evidence is persuasive—and indeed nearly everyone has known people who are particularly gifted in one or more of these areas but all too average, or even deficient, in some of the others.

Yet despite these and other challenges and oppositions to standard IQ testing, it continues to be “one of psychology’s greatest successes,” writes Etienne Benson, a staff member of
Monitor on Psychology
, an online publication of the American Psychological Association. “It is certainly
one of the field’s most persistent and widely used inventions.”
⁶⁷
Many of the biases identified by critics of intelligence testing have been reduced, she says, and since the 1970s the field has acquired more sophisticated methods of interpretation, more advanced statistics, and new, methodologically more sophisticated, tests.
⁶⁸

In addition to all the uses made of IQ testing, it also is an essential tool for various kind of neurological research. Psychologists have long wondered whether the brains of highly intelligent people differ, physically, from those of average people. A new study initiated by the National Institute of Mental Health, relying on brain scans by magnetic resonance imaging over a period of seventeen years, has shown that the cortex— the outer sheet of neurons covering the brain that is the seat of many higher mental processes—grows thicker than average in highly intelligent children as they age and then thins out later, ending up even thinner than average. “This is the first time that anyone has shown that the brain grows differently in extremely intelligent children,” says Paul M. Thompson, a brain-imaging expert at the University of California at Los Angeles. Apparently, the brains of the highly intelligent children are rewiring themselves, developing fruitful connections among the neurons and later pruning out redundant ones, thus operating more effectively during childhood and remaining more effective in adulthood. And here’s the point: All the data on the different growth of these children’s brains would tell us nothing about intelligence were it not for the IQ tests and scores taken along with the scans.
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The IQ controversy has raged, died down, and raged again; politics beclouds science, and science is used for political ends. The struggle continues and shows no signs of ending, but lineal descendants of the early intelligence tests, now greatly modified and more nearly “culture-fair” than the early tests, are widely used in schools, institutions, the military, industry, and elsewhere.

Whatever one calls them, and whatever one’s stance on intelligence testing, the fact remains that mental measurement is useful, is beneficial to society (though not in the way Goddard and Terman had in mind), and remains one of psychology’s major contributions to modern life in America and most other developed nations.

B
y the late 1890s, humankind, after some twenty-four centuries of speculation about how the mind works, seemed on the verge of understanding it. The followers of Wundt and James were, in their different ways, introspectively examining their conscious sensations and thoughts; Freud was peering into the murky depths of his own unconscious and that of his patients; and Binet was preparing to measure the growth of the intellect throughout childhood.

Why, then, were a number of psychologists and physiologists playing little tricks on animals that could tell nothing about their inner experiences, and calling it psychological research?

How could it advance the understanding of the human mind to offer a baby chick two kinds of caterpillars, one of which presumably tasted bitter? (“Presumably” because it appears that the researcher himself never tasted it.) Or to soak some kernels of corn in quinine, others in sugar water, dye them different colors, and strew them before chickens? The baby chicks pecked at both kinds of caterpillar and shortly began to avoid the bitter ones, and the chickens soon ate only the sweetened kernels of corn, but what did any of that have to do with human learning?
¹

How could any of the great questions of psychology be answered by putting a hungry cat in a slatted “puzzle box” from which it could escape only by stepping on a treadle that opened a door? After placing the cat inside and latching the door, the researcher set a scrap of fish outside. The cat, galvanized by the sight and smell of the fish, pressed its
nose into the space between the slats, thrust its paws through, then backed away and scrambled wildly around the cage for two and a half minutes until it happened to step on the treadle, causing the door to fall open. Out popped the cat to eat the bit of fish—only to be put back in the box for another try. It did better the second time (forty seconds to escape), worse the third time (ninety seconds), and only after over twenty trials promptly released the door each time.
²
A tiny addition to knowledge, no doubt—knowledge about cats. But what did that have to do with people?