The Handy Psychology Answer Book. Lisa J. Cohen

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СКАЧАТЬ to large groups would be most useful. Potential soldiers falling below a cut-off point would be excluded from the military, while high scorers could be selected for elite positions.

      Under the guidance of Robert Yerkes (1876–1956), a Harvard psychologist and army major, the Army Alpha, a written test, and the Army Beta, a pictorial version for the 40 percent of soldiers unable to read the written test, were developed. These tests had broad impact on the discharge and promotion of soldiers. The use of such tests in WWI spawned an explosion of intelligence and aptitude tests after the war to be used in schools, the military, and other institutions.

      Criticism of cultural bias soon followed, with complaints that the content of the Army tests favored affluent, native-born Americans over less privileged immigrants, who could not be expected to know, for example, the engines of different luxury cars or the layout of a tennis court. Further, many questions were moralistic, as if disagreement with Anglo-American values reflected lower intelligence. Despite these very legitimate complaints, it must be kept in mind that these intelligence tests aimed for a merit-based approach to job placement. In this way, the army at least tried to be more democratic than the explicitly prejudiced, family and class-based approaches to employment that were typically used before. Today’s intelligence and aptitude tests aim for much greater cultural sensitivity. Nonetheless, it is arguably impossible to develop a test that is completely culture-neutral.

      Who devised the first intelligence test?

      Frances Galton (1822–1911), the father of Eugenics, was one of the first scientists to study individual differences in intelligence. He presumed such differences were inherited, what we would now call genetic, and he aimed to separate the most intelligent individuals from the least in the interest of selective breeding. In keeping with Wilhelm Wundt’s studies of sensation and perception, Galton’s initial intelligence tests comprised various measures of hand grip, reaction time to sensory stimuli, and other sensory-motor skills. James Cattell (1860–1944) carried this work forward and developed an intelligence test based on Galton’s work. In his position as professor of psychology at Columbia University, he administered his test to hundreds of college freshmen. (Perhaps this was the beginning of the long tradition of using college freshmen in psychological research.)

      By 1901, Cattell had sufficient data to correlate students’ grades with their intelligence test results. To his great disappointment, there was no relationship at all between the two variables. We might attribute these negative findings to two factors: a lack of construct validity, such that psychophysical measures have no relationship at all to academic performance, and restriction of range. College freshmen at an elite university will not vary that much in intelligence, so some correlations with intelligence may be masked by this fact.

      What was the Binet-Simon test?

      Influenced by a mandate from the French government addressing the needs of mentally retarded children, Alfred Binet (1857-1911) and his colleague Théodore Simon (1872–1961) decided to develop a test capable of distinguishing mentally retarded children from those of normal intelligence. They did this through multiple administrations and refinements of their measure, giving the test both to children of normal intelligence and those identified as mentally retarded. The first version of their test was published in 1905, with several revisions following in quick succession. By providing the expected scores for each age in the 1908 edition, Binet and Simon created the first empirically validated, standardized test. Within a few years, the Binet-Simon test was being used by countries on five continents.

      What is the Stanford-Binet intelligence test?

      Lewis M. Terman (1877–1956) at Stanford University revised and refined the Binet-Simon test to increase its sensitivity at the higher end of the scale. The Stanford-Binet test, published in 1916, was the first test to use IQ scores. An IQ score (or intelligence quotient) is derived from a large sample of test results. Terman set the mean IQ score at 100 and the standard deviation at 10. By translating raw scores into IQ scores, the percentile rank of each score could be calculated. For example, an IQ score of 100 falls in the 50th percentile, of 80 in the 2.5th percentile, and one of 130 in the 99th percentile. The Stanford-Binet was the primary IQ test used for many decades and is currently in its fifth edition. In 1958, two years after Terman died, David Wechsler published the Wechsler Adult Intelligence Test (WAIS), which is now the more widely used IQ test.

      What were the problems with the early IQ tests?

      The problem with Galton’s approach was an utter lack of relationship between outside indications of intelligence, such as school performance, and the measures used. His tests had more to do with physical coordination and strength than intelligence and as such had no construct validity. Later tests also had problems with validity but these were more subtle. For the most part, they were extremely culturally biased, serving the anti-immigrant bias of the first several decades of the twentieth century. Here the biggest problem was generalizability, meaning the applicability of the test to a larger population. Some items only measured knowledge available to wealthy, English-speaking, and native-born Americans. Other items measured moral values more than strict intellectual skills. Later IQ tests addressed these problems by including non-verbal tests, considering cultural relevance when including items, and basing test norms on samples carefully constructed to match the demographics of the United States.

      What does mental age mean?

      Alfred Binet (1857–1911), a French psychologist, furthered the work of Galton and Cattell with his concept of mental age. While observing his own children develop new cognitive skills as they grew, Binet recognized that intelligence could be measured developmentally. By comparing the test performance of a child with the age at which such performance was expected, he could calculate a mental age for each child.

      THE BRAIN: ANATOMY AND DEVELOPMENT

      BASIC CONCEPTS IN NEUROSCIENCE

      Why do we study the brain?

      As early as 500 B.C.E., Alcmaeon of Croton identified the brain as the physical seat of the mind. Twenty-five hundred years later, modern science has proven this ancient Greek to be absolutely correct. There is no aspect of psychology that is independent of the brain. The very essence of our humanity—our thoughts, our feelings, our beliefs, and our values—all emerge from this three-pound lump of gray tissue. Moreover, with the remarkable advances of neuroscience in the last few decades, we now know more about the brain and its relationship to the mind than at any other time in human history.

      What do neuroscientists assume about brain evolution and how does that influence our understanding of the brain?

      In order to understand brain research, it is important to consider three basic assumptions that neuroscientists make about brain evolution. For one, the brain is believed to carry traces of its evolutionary origins deep within its tissues. Just as we carry traces of our earliest childhood within our adult personalities, the brain carries the history of our whole species within its very anatomy. Secondly, the brain has evolved up and out, so that the lowest and deepest parts of the brain are the oldest. The outermost, uppermost, and the furthest forward brain regions are the youngest on the evolutionary scale. Thirdly, our brains have increased in complexity across evolution. The older structures tend to be simpler and more primitive, both in their anatomy and in the behavioral functions they control. СКАЧАТЬ