Definitions Of Intelligence

Transcription

1 Intelligence

2 Definitions Of Intelligence As a result of the evolution of ideas, intelligence, or goal-directed adaptive behavior, has not been always conceived in the same way. The work of Francis Galton and Alfred Binet serves as a historical example of this process. Their approaches to understanding intelligence differed. Galton used the psychophysical approach while the Binet focused on judgments. However, both agreed that intelligence could be measured.

3 Francis Galton: Measuring Psychophysical Performance Galton was one of the first to explore the implications of his cousin Darwin's theory as it related to intelligence. Galton proposed two qualities to identify the intellectually gifted: energy and sensitivity to physical stimuli. Galton also believed in the notion of eugenics, or the idea that intelligence and other abilities could be increased in humans through careful breeding.

4 James McKeen Cattell Many of Galton's ideas were brought to the United States by James McKeen Cattell, who continued to develop a series of psychophysical tests. The assumption made by both Cattell and Galton was that those tests would measure mental ability. However, Wissler, one of Cattell's own students, correlated the results of these tests with student grades and found no relationship. Because of this result, many believe Cattell was measuring something other than intelligence.

5 Alfred Binet: Measuring Judgment In 1904, Binet was asked to develop a method of identifying children with lower than normal intelligence who would be unlikely to benefit from school instruction. He and Theodore Simon, his collaborator, developed a test that emphasized judgment as the basis of intelligence. They criticized Galton's methods as emphasizing sensory acuity, while claiming that mental judgment, (good, practical sense) was the key to intelligence. For them, intelligent thought involved the ability to reason well and adapt to one s circumstances.

6 Mental Age In The Intelligence Quotient Instead of classifying schoolchildren in terms of their physical or chronological age, they believed that children should be classified by their mental age, or their relative intelligence compared to a hypothetically "average" child of the same chronological age. For example, a six-year-old child who performs at a level similar to the average 10- year-old child would have a mental age of 10 years.

7 Mental Age In The Intelligence Quotient Similarly, a six-year-old child who performs at the level similar to an average four-year-old child would have a mental age of four years. So, a child could be "ahead" of or "behind" his or her age mates in this scheme. Children, therefore, could be placed in school according to their mental ages rather than their chronological ages.

8 William Stern, however suggested that a ratio, the intelligence quotient (IQ), would be more useful in classification of children of different ages. The intelligence quotient was defined as the mental age (MA) divided by the chronological age (CA), multiplied by 100, or: IQ equals MA/CA x 100

9 Hence, average intelligence was considered a score, or IQ, of 100. Scores below 100 indicated lower intellectual ability, and scores above 100 indicated higher intellectual ability. Stern's formula for IQ is known today as ratio of IQ.

10 However, the utility of mental age and measurement has been problematic because it does not successfully gauge intelligence across the lifespan. Children make large gains in intelligence early in life, but as they age, mental age changes less and less. Mental age is not well-suited to lifespan intellectual comparisons.

11 Intelligence Tests

12 The Stanford-Binet Intelligence Scales Lewis Terman, a psychologist from Stanford University, translated Binet and Simon's test into English and changed the scoring to a ratio of IQ system. Since that time the test that Binet and Simon created has been known as the Stanford- Binet Intelligence Scales. While the Stanford-Binet is still widely used, the Wechsler series of tests has become even more popular.

13 The Wechsler scales David Wechsler created a series of similar age-based intelligence tests. The current versions are: The third edition of the Wechsler Adult Intelligence Scale (WAIS-III) The third edition of the Wechsler Intelligence Scale For Children (WISC-III) The Wechsler Preschool And Primary Scale Of Intelligence (WPPSI). All these tests are deviation IQs.

14 Deviation IQ Deviation IQ: Scores based on a person s relative standing in his or her age group; how far above or below average a person s score is, relative to other scores

15 The Wechsler scales They each yield three scores: a verbal score, a performance score, and an overall score. Based on separate batteries of tests, the verbal score is generated from tests that rely more heavily on verbal abilities. The performance score is generated from tests that rely more heavily on nonverbal abilities and speed of performance. The overall score is derived from a combination of these two scores.

16 IQ scores are not very dependable until a child reaches age 6 Terminal Decline: Abrupt decline in measured IQ about 5 years before death Men and women do not appear to differ in overall intelligence A correlation (about.50) exists between IQ and school grades

17 Aptitude In Achievement Tests Galton and Binet unwittingly started a tradition of testing intellectual and cognitive abilities that continues today. Many kinds of tests are currently available. However, not all measures of cognitive ability measure intelligence. Some measure aptitudes, defined as an obtained level of expertise, such as in music, athletics, or computers. These tests are designed to measure an individual's potential to perform in a given area.

18 Other tests measure achievements, or accomplishments, either separately, or in conjunction with aptitude. The Scholastic Assessment Test (SAT) is an example of this type of test. Achievement tests generally are designed to measure mastery of the content area rather than potential.

19 Score Distributions Because ratio IQs (based on mental age) were not useful descriptors of intelligence, measurements today are expressed in relation to the normal distribution, percentiles, and deviation IQs.

20 Normal Distributions For many psychological measures, including intelligence, it is theorized that these characteristics are normally distributed in the human population. In other words, if it were at all possible to measure the intelligence of every single person in the world, we would expect to find that the majority of individuals would perform similarly (or what we would refer to as average).

21 Normal Distributions We would expect lower numbers of individuals performing either very well or very poorly in relation to all the others, creating what is referred to as the bell curve. So one way of understanding intelligence is to express where a person falls within this bell curve or normal distribution of intelligence.

22 Distribution of IQ

23 Measures of Central Tendency One way to think of the middle of the IQ distribution is in terms of the median, or the middle score within the distribution. Another, is the mean, or the average score within the distribution. The third way, is in terms of the mode, which is the most frequently obtained score. In a normal distribution, these three measures are the same score or measure.

24 Deviation IQs Another means of comparing individuals on tests of intelligence is through deviation IQs. Deviation IQs generate a score that is based on characteristics of the normal distribution.

25 Recall that average IQ is 100. One standard deviation from this average is considered 15 points. Consequently the majority of individuals would be expected to score between 85 and 115 on an IQ test since this represents one standard deviation from the mean in either direction.

26 Two standard deviations from the main would include scores between 70 and 130 and is believed to encompass 96% of the population. Scores outside these ranges (below 70 or above 130) are believed to represent extremes of intelligence because they fall outside two standard deviations from the mean and would only occur in 4% of the population (2% below a score of 70 and 2% above a score of 130).

27 Today, raw scores on an IQ test are converted into deviation IQs. Thus, today's IQ score reflects not only where in the normal distribution the person performed, but what percentiles his or her score corresponds to and how far the score deviates from the average ability in the population.

28 Giftedness Having a high IQ (usually above 130) or special talents or abilities (playing Mozart at age 5)

29 Marilyn Mach vos Savant With a score of 230, she has the highest IQ ever officially recorded. At age 7 years 9 months old, she could answer questions that the average 13 year old could answer.

30 Marilyn Mach vos Savant At ages 8, 9, & 10 she got a perfect score on the Stanford- Binet scale.

31 Masoud Karkehadadi Started speaking at 8 months At 18 months memorized the top tunes on MTV Scored 100% on high school equivalency test at age 7 Graduated from UC Irvine at 12 IQ over 200

32 Mental Retardation (or Developmental Disabilities): Some Definitions Presence of a developmental disability and an IQ score below 70; a significant impairment of adaptive behavior also figures into the definition Adaptive Behavior: Basic skills such as dressing, eating, working, hygiene; necessary for self-care Familial Retardation: Mild mental retardation that occurs in homes that have inadequate nutrition, intellectual stimulation, medical care, and emotional support

33 Organic Causes of Mental Retardation Related to physical disorders Birth Injuries: Lack of oxygen during delivery Fetal Damage: Congenital problem; prenatal damage from disease, infection, or drug use by the mother Metabolic Disorders: Disorder in metabolism; affects energy use and production in the body Genetic Abnormalities: Abnormality in the genes, such as missing genes, extra genes, or defective genes

34 Types of Organic Causes Phenylketonuria (PKU): Genetic disease in which the child lacks an important enzyme. Allows phenylpyruvic acid to accumulate in the body If untreated, severe retardation may occur by age 3 Routine medical tests at birth can detect PKU Treat with phenylalanine-free diet (found, for example, in Aspartame, known as Nutrasweet)

35 More Organic Causes of Mental Retardation Microcephaly: Head and brain are abnormally small; brain is forced to develop in a limited space Hydrocephaly: Buildup of cerebrospinal fluid within the ventricles (brain cavities); pressure can enlarge the head and damage the brain Cretinism: Stunted growth and retardation caused by insufficient supply of thyroid hormone May also be caused by lack of iodine Easily detected in infancy

36 Down Syndrome Down Syndrome: Genetic disorder caused by presence of extra chromosome (usually on the 21st pair; trisomy 21); results in mental retardation and shorter life span Does not run in the family Older a woman is, greater the risk to produce a Down s child Older fathers also contribute (about 25% of the time) No cure, but is detectable before birth

37 Fragile X Syndrome Fragile X Syndrome: Genetic form of retardation caused by defect in X chromosome Runs in families Sex-linked; mainly affects boys Most suffer from hyperactivity and attention disorders Become more severely retarded as adults

38 Assessment Issues This has to do with evaluating the quality of the test. As we saw, Wissler (Cattell's student) debunked Galton's notion of intelligence when he evaluated it. Several factors are considered when designing tests. These include validity, reliability, and standardization.

39 Validity Validity concerns whether a test measures what it says it is measuring. For example, a test that has been designed to measure depression, if valid, should discriminate between people who are depressed and those who are not. Similarly, tests of intelligence, if valid, should distinguish between individuals who are intelligent and those who are not.

40 Construct-related Validity Construct-related validity relates to the degree of fit between a test and a theoretical construct it supposedly measures. So, if we have designed a test that measures personality, the test should fit with our theoretical notion of personality. Tests of intelligence, therefore, should measure our conceptualization of intelligence. Today it is easy to see how Galton's psychophysical tests lacked construct validity, as our understanding of intelligence is much different than it was in his time.

41 Do high IQs predict later ability? Lewis Terman selected 1500 children with IQs of 140 or above. He followed this group (he called Termites ) into adulthood. By doing this he countered a number of misconceptions about high intelligence.

42 The Termites Misconception: The gifted tend to be peculiar, socially backward people. Fact: On the contrary, Termin s gifted subjects were socially well-adjusted and showed above average leadership.

43 The Termites Misconception: Early ripe means later rot: the gifted tend to fizzle out as adults. Fact: When they were retested as adults, Terman s subjects again scored in the upper IQ range.

44 The Termites Misconception: The very bright are usually physically inferior eggheads or weaklings. Fact: As a group, the gifted were above average in height, weight, and physical appearance.

45 The Termites Misconception: The highly intelligent person is more susceptible to mental illness ( Genius is next to insanity. ) Fact: Terman demonstrated conclusively that the gifted have better than average mental health records and a greater resistance to mental illness. In general, the highly gifted tend to be well adjusted physiologically and socially.

46 The Termites Misconception: Intelligence has nothing to do with success, especially in practical matters. Fact: The later success of Terman s subjects was the most striking finding of the study. Far more of them on average had completed college, earned advanced degrees, and held professional positions. As a group they had produced dozens of books, thousands of scientific articles and hundreds of other publications.

47 Reliability Reliability, another factor considered when constructing the test, is a measure of consistency. Reliability and validity together determined in large part the usefulness of a test. Reliability also comes in several forms. Test-retest reliability is measured by having the same test takers repeat an identical test within a short period. If the test is reliable, we would expect similar performance scores from one time to the next.

48 Reliability Alternate-forms reliability is measured by creating two similar forms of the same test and giving them to the same test takers at closely spaced times. Again, if the test is reliable, we would expect similar scores on the two versions. Internal-consistency reliability is a measure whether test items measure the same thing.

49 Reliability Lastly, Inter-rater reliability measures whether two or more judges rate the same response in the same way. You may notice this type of reliability in the sports of figure skating and gymnastics. Often the judges, one rating a skater or gymnast, independently rate the performance similarly. Of course, you also may have witnessed when one or more judges are way off base (less reliable) from the other judges, as was the case with the judge for figure skating during the 2002 Winter Olympics.

50 Standardization and Norms Most tests are standardized. Standardization ensures that the conditions surrounding the administration of a test are similar for all test takers. Group paper and pencil tests are easily standardized, but individually administered oral tests require a level of training for test givers before they can be said to be standardized. Standardization allows tests to be used to compare large numbers of test takers over the many years in the lifetime of the test through the calculation of normative scores or norms. Norms scale the raw scores into equivalent scores which reflect the relative levels of performance of the various test takers.

51 Charles Spearman: The g Factor Charles Spearman's interpretation of his factor analytic studies led him to believe that a single general factor, g, could account for most of the variance in people's performances on tests of intelligence. Other sets of specific factors, s, each relating to a single type item (e.g., arithmetic), also influenced one's mental ability, but g was far more important than s because of g's wideranging applicability.

52 Louis Thurstone: Primary Mental Abilities Louis Thurstone expanded the number of factors responsible for intelligence to seven equally important primary mental abilities: (1) verbal comprehension, (2) verbal fluency, (3) inductive reasoning, (4) spatial visualization, (5) number, (6) memory, and (7) perceptual speed.

53 Raymond Cattell and John Carroll: Hierarchical Models Raymond Cattell proposed a hierarchical model of intelligence, which allows for a more parsimonious way of handling factors. His model divides general intelligence into two sub factors: fluid intelligence and crystallized intelligence.

54 Raymond Cattell and John Carroll: Hierarchical Models Fluid intelligence involves one's ability to reason abstractly and inductively. Crystallized intelligence involves one's accumulation of knowledge and general information. Within these two sub factors are more specific factors or abilities.

55 Simple Information Processing An example of a simple process to account for intelligence is inspection time. In looking at a simple stimulus such as two vertical lines, inspection time involves how long it takes a person to discriminate which line is longer. Studies have found that more intelligent individuals (as measured by other tests) have shorter inspection times.

56 Metabolic evidence Another area of investigation related to physiological processes is the amount of glucose the brain metabolizes (as measured by a PET scan) when engaged in a mental task. Overall glucose consumption in the brain appears to be lower in more intelligent subjects, but more intelligent subjects also show higher consumption of glucose in some areas of the brain that may relate to the particular task under investigation. This suggests again a relationship between brain efficiency and intelligence. However, further study is needed to replicate these findings.

57 Brain size Not only have the workings and metabolism of individual brain cells been examined in relation to intelligence, but another line of research is looking at the relationship between the overall size of the brain and the amount of intelligence. There is evidence that there is, in humans, a modest, but significant statistical relationship between larger brains and increased intelligence. However, these results are subject to the "chicken and egg problem", meaning which one came first-- larger brains equal increased intelligence, or increased intelligence equals larger brains?

58 Culture-Fair Testing All of this research suggests that developing a culture-fair test, a test that is equally appropriate for members of all cultures, would be impossible because various cultures have different notions about intelligence. Even the most seemingly prized basic cognitive skills (e.g., mental quickness) may be viewed in an opposite manner by other cultures. So, a search for culture fairness is doomed from the start.

59 Culture-Fair Testing However, cultural-relevant tests may be possible to create. Culture-relevant tests would measure intelligence within particular cultural or situational contexts. Existing data have shown that intelligent performance does vary widely as a result of context across and even within many cultures. Social factors such as gender, race, or income level may influence one's expression of intelligence from one context to the next.

60 Fig No intelligence test can be entirely free of cultural bias. However, culture-fair intelligences test try to minimize the effects of growing up in various cultures. The following sample items are from a culturefair test. 1. Which pattern is different from the remaining four? (Number 3.) 2. Which of the five figures on the right would properly continue the three on the left_that is, fill in the blank? (Number 5.) 3. Which of the figures on the right should go in the square on the left to make it look right? (Number 2.) 4. At left, the dot is outside the square and inside the circle. In which of the figures on the right could you put a dot outside the square and inside the circle? (Number 3) (Courtesy of R.B. Cattell).

61 Gregg Cox At age 34 could speak 64 different languages. Per Guiness Book of World Records he is the planet s greatest linguist. At age 5 began learning Spanish, Portuguese, Italian, German & Chinese

62 Venus Williams At age 20, first black woman to win Wimbleton Then beat number 1 ranked woman to with the U.S. Open Won gold medal in 2000 Olympics Winnings in millions, has chance to become the greatest woman tennis player of all time

63 Bill Gates At 45 richest man in the world net worth of $61 billion Began writing computer programs in eighth grade. Dropped out of Harvard to write one of the first operating systems for computers Company Microsoft operates 90% of the world s computers

64 D. Steve Lu At age 5, scored 194 on IQ test Finished 12 years of pre-college classes in 5 years Freshman in college at age 10 At 15, accepted into graduate computer science program at Stanford University.

65 E. Midori Began playing violin at age 3 By age 10 considered musical prodigy as she performed with NY Philharmonic. At very early age able to memorize and flawlessly performed complicated pieces of classical music.

66 Howard Gardner: Multiple Intelligences Gardner has proposed the theory of multiple intelligences in which eight separate intelligences: linguistic, logicalmathematical, musical, spatial, bodilykinesthetic, interpersonal, intrapersonal, and naturalist, interact to produce intelligent behavior.

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68 Howard Gardner: Multiple Intelligences Gardner's evidence for the various intelligences was derived from a variety of sources, including the effects of brain damage, research on typical developmental processes, studies using individuals considered exceptional intelligence, and factor analysis. For example, the feature movie Rainman had Dustin Hoffman play an autistic savant, one of the exceptional sources of Gardner s theorizing. The savant can be thought of as a person with highly developed intelligence, numerical in the case of the character played by Hoffman.

69 Howard Gardner: Multiple Intelligences Theories such as Gardner s are sometimes called modular because each intelligence can be thought of as stemming from a distinct brain area. As intriguing as Gardner s theory is, hard evidence for it is still lacking. Moreover, additional types of separate intelligences such as emotional intelligence or social intelligence also have been proposed, suggesting the Gardner s theory may not encompass the entire range of behaviors that are involved in intelligence.

70 Sex Differences Changes in group differences on intelligence tests can be easily illustrated by looking at gender. Sex differences on cognitive-ability tests have been steadily shrinking over the years. However, some differences do remain. On average, males tend to score higher on tests that require visual and spatial memory, aiming of motor skills, and certain mathematical tasks. Females tend to score higher on average on tasks that require rapid access to and use of verbal information from long-term memory, fine motor skills, and perceptual speed.