2 Measuring Intelligence: A Brief History Intelligence tests were invented a little over 100 years ago by 1 (last name) in order to identify mentally subnormal children in a way to avoid complete reliance on teachers evaluations which might often be 2 and biased.Theodore Simon created the first useful test of general 3 ability that was capable of predicting children’s performance in school fairly well. This Binet-Simon Scale gave a scored a child’s 4 (2 words) . Mental age indicated that a child displayed a mental ability typical of a child that 5 age (i.e., a child may have a mental age of 10, even though s/he is 6 years old)Sir Francis Galton, 1869, published Hereditary Genius, in which he put forth the notion that success runs in families because intelligence is inherited. He developed a crude mental abilities test based on sensory acuity.Alfred Binet and Theodore Simon, in an effort to devise a test to identify children who would need special training in school, published the first intelligence test in Using this test, a child’s score was in terms of mental age. For example, a 4 year old child with a mental age of 6 would have performed like the average 6 year-old on the test.Lewis Terman, at Stanford University, revised Binet’s test for use in the U.S.–the Stanford-Binet.Terman used a new scoring scheme, the intelligence quotient suggested by William Stern, dividing a child’s mental age by chronological age and multiplying by 100…this IQ ratio placed all children (regardless of age) on the same scale, which was centered at 100 if their mental age equaled their chronological age.David Wechsler was the first to devise an instrument to measure intelligence in adults. He later devised downward extensions of his scale for children. Wechsler is credited with two innovations in intelligence testing. First, his scales give more emphasis to nonverbal reasoning, yielding a verbal IQ, a performance IQ, and a full-scale IQ. Second, Wechsler devised a new scoring system based on the normal distribution.
3 Measuring Intelligence: A Brief History Terman devised “IQ” or _6_(2 words)_ from the formula: (Mental Age ÷ Chronological Age) X 100Therefore if one’s Mental and Chronological age is the same one’s IQ would be # (7).David Wechsler created the first high-quality intelligence test designed specifically for It is still used today and is called the Wechsler Adult Intelligence Scale or 9 , for short.Wechsler improved IQ testing by:making a distinction between 10 and non-verbal abilitybasing his scoring scheme around the 11 (2 words).
4 The Normal Distribution: Interpreting the Modern IQ The normal distribution is a “12 (2 words)” curve that represents the pattern in which many characteristics (including intelligence scores) are distributed across the population.If IQ scores are “normal” then most scores are found around the middle of the distribution (the average score, the 50 percentile).For 13 IQ tests the average or “mean” score at 100 points and the standard deviation at 15.A score indicates the percentage of people who score at or 15 the score one has obtained.
5 The Normal Distribution The Normal Distribution. Many characteristics are distributed in a pattern represented by this bell-shaped curve. The horizontal axis shows how far above or below the mean a score is (measured in plus or minus standard deviations). The vertical axis is used to graph the number of cases obtaining each score. In a normal distribution, the cases are distributed in a fixed pattern. For instance, 68.26% of the cases fall between +1 and –1 standard deviation. Modern IQ scores indicate where a person’s measured intelligence falls in the normal distribution. On most IQ tests, the mean is set at an IQ of 100 and the standard deviation at 15. Any deviation IQ score can be converted into a percentile score.
6 Reliability and Validity of Intelligence Tests A 16 test is one that yield similar results each time it is repeated. For example, if you scored 120 on an IQ test each time you took it…it is a “reliable test”.It is important to understand that just because a test is reliable does not make it “meaningful” or “accurate”.A meaningful test is called “Valid”. Specifically, 17 refers to the ability of a test to measure what it is designed to measure. For example, if an IQ test correctly predicts future performance in school, it could be said that this test is valid.Sternberg has argued IQ tests should be valid measures of at least 3 kinds of intelligence: Verbal, Practical, & Social, but most only measure 18 intelligence.
7 Heredity & Environment as Determinants of Intelligence The average correlation for identical twins is very high indicating that identical twins tend to be quite 19 in intelligence, While slightly lower, the correlations remain strong even if twins are reared apart.Based on research of how similar the IQs are of related and non-related persons, scientists have suggested that the heritability of IQ (what percent of intelligence is inherited) is about 20 (#-percentage) % at the “high end”.EnvironmentThere is plenty of evidence that the way one is brought up affects intelligence as well. The 21 (2 words) hypothesis suggests that children who are raised in substandard circumstances should experience a decrease in IQ as they grow older. Conversely, if children are raised in an “enriched” environment they will benefit. Research generally supports both of these.Whether intelligence is inherited or due to environmental influences continues to be argued; however, it is becoming clear that both influence intelligence.Family studies determine only whether genetic influence on a trait is plausible, not whether it is certain. Family members also share environments.Twin studies provide evidence regarding the role of genetic factors. The basic rationale is that identical and fraternal twins develop under similar environmental conditions, but identical twins share more genes…if identical twins end up more similar on a given characteristic, it must be genetic.A heritability ratio is an estimate of the proportion of trait variability in a population that is determined by variations in genetic inheritance. A heritability estimate is a group statistic and cannot be meaningfully applied to individuals.Adoption studies provide evidence that upbringing plays an important role in mental ability, as adopted children show some resemblance to their foster parents. Also, siblings reared together are more similar in IQ than siblings reared apart. In fact, entirely unrelated children who are reared together show resemblance in IQ.The cumulative deprivation hypothesis holds that children raised in deprived environments will experience a gradual decline in IQ as they grow older. Conversely, children removed from deprived environments and placed in homes that are more conducive for learning show IQ increases.The Flynn effect is the trend all over the developed world for IQ scores to increase from one generation to the next. Hypotheses for why this occurs focus on environmental variables, as evolution does not operate in a generation.Clearly, heredity and environment both influence intelligence. Theorists use the term reaction range to refer to genetically determined limits on IQ. The environment determines whether a person will fall at the upper or lower end of their genetically determined range.
8 Heredity & Environment as Determinants of Intelligence InteractionThe concept of the 22 range refers to genetically determined limits on IQ (or other traits).The current thinking is that heredity may set certain limits on intelligence and that environmental factors determine where individuals fall within these limits. That is, genetic makeup places an 23 limit on a person’s IQ that can’t be exceeded even when environment is ideal.Also there is a lower limit on IQ even if environment is a deprived one.Kamin and others disagree with Arthur Jensen. They argue that the cultural differences seen in IQ scores, are not caused by genetic differences.These scientists contend that IQ scores are depressed because children in minority groups tend to grow up in 24 (2-words) that create a disadvantage– both in school and on IQ tests.
9 New Directions in the Assessment and Study of Intelligence Exploring Biological Indexes of IntelligenceThe search for a “culture-free” measure of intelligence have led investigators to focus on sensory processes, raw physiological indicators of intelligence. Two examples are: 25 times and 26 times.Both Robert Sternberg and Howard Gardner have suggested that there are a variety of kinds of intelligence.In the most recent extension of Sternberg’s triarchic theory of human intelligence, he has asserted that there are three aspects or facets of “successful intelligence”– 27, 28 and 29 intelligences.Gardner suggests the existence of a number of relatively independent human intelligences. He has concluded humans exhibit 30 (give the number here) intelligences: Logical-Mathematical, linguistic, musical, spatial, bodily-kinesthetic, interpersonal, intrapersonal, & naturalist. There has been little research investigating Gardner’s theory however.Aurthur Jensen, Hans Eysenck, and other researchers are searching for physiological indicators of general intelligence, which will be “culture free”. Reaction time has been used in these studies, although the “fast is smart” idea is modest at best. Other measures studied include inspection time, which is an assessment of how long it takes to make simple perceptual discriminations that meet a certain criterion of accuracy. Higher correlations with IQ have been found with this measure, although much work remains to be done to discover why.For over a century, intelligence was approached from a testing perspective. In contrast, the cognitive perspective focuses on how people use their intelligence. Robert Sternberg’s triarchic theory of intelligence consists of three parts: the contextual, experiential, and componential subtheories. In more recent years (1999, 2000) Sternberg has asserted that there are three aspects of what he calls “successful intelligence”–analytical intelligence, creative intelligence, and practical intelligence.Other theorists propose an expansion of the concept of intelligence. Howard Gardner argues that IQ tests emphasize verbal and mathematical skills and exclude other important skills. He suggests the existence of a number of human intelligences, listed in table 9.3.Daniel Goleman and others argue for the concept of emotional intelligence, which is the ability to perceive and express emotion, assimilate emotion in thought, understand and reason with emotion, and regulate emotion.