Module 2 - Intelligence PDF

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By Professor Nick Burns...

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Lecture 1 {SLIDE 1} Hello, my name is Nick Burns. Welcome to this series of presentations on the topic of human intelligence. This is a really interesting area of psychology and I hope you enjoy these presentations and the associated reading and other activities, including the workshops where we will look at some of the topics in a little more detail. {SLIDE 2} This is the first of five presentations on the topic of intelligence. These follow the layout in your textbook but we will not cover the section on group differences. The first presentation provides an historical perspective with the intention of arriving at a definition of intelligence. Clearly, we need to have a definition that we can agree about if we are going to attempt to measure intelligence. Now the reason that we're going to spend time talking about the question of what is intelligence is that it's actually quite difficult to find a definition about which most people can agree. {SLIDE 3} Here are the learning objectives for this presentation. Firstly, I'm going to go through the history of how intelligence has been defined - this was guided by what I will call implicit theory, or common sense understandings. Then we're going to look at how tests of intelligence were developed, which requires a bit of twentieth century history. Finally, I am going to introduce you to the intelligence test that is the most common ly used today – the Wechsler Intelligence Scales. {SLIDE 4} What you see here are the sorts of responses you would get from lay people on what they think intelligence is. People would say that it was important to be able to cope with new situations; they would talk about being able to solve problems; they would talk about verbal expression and number ability; they would talk about being able to deal with abstract situations; they would include some ideas about social competencies; and they would talk about people having quick minds; and they would say that it 's going to have something to do with learning and memory. These sorts of responses illustrate implicit theory. Now from the point of view of psychology we regard these terms as what we call constructs; or, more formally, latent constructs. We refer to these capacities, like memory, or learning ability, or intelligence, as constructs because implicitly we know they must exist because our minds tell us that this is so. Psychological science actually depends a great deal on the use of constructs; we use them to describe things that are not directly observable. We can observe intelligent behaviour, that is, behaviour that we would deem to be intelligent. But we can't actually say we can directly observe mental speed, or memory. The point of constructs is that we can eventually develop better explanations. If we can break down intelligence into these various constructs then we can go about the business of attempting to develop measures of these and then gradually build up a description of what we think intelligence is. That is how we have reached the present state with the definition that we have. By consensus, it is the case that since psychologists started looking to see if they could develop measures of intelligence, that intelligence was strongly linked to educational achievements. This is because there's been a consensus right from the beginning that for a child to do well at school, the child had to be intelligent. If a child did not do so well at school, the child may not be so intelligent. Now it's also the case that there are some sorts of things that you could include which aren't included in the definition. The reason for that is that by consensus some activities are excluded even though they are highly valued by our culture. No one argues about whether we value intelligence or not, it's absolutely obvious that we do but we pretty obviously also value, for example, excellence in sport. We value excellence in music, we value excellence in art, and so on. There are some theorists of intelligence who argue for the inclusion of these and other constructs as part of a definition of intelligence. For example, Howard Gardner has proposed a theory of multiple intelligences, which we will talk about in the next presentation. {SLIDE 5} This is the definition of intelligence from your textbook. Intelligence is the ability to acquire knowledge, to think and reason effectively and to deal adaptively with the environment. {SLIDE 6} Here are the important parts of the definition. Notice that the definition specifies ability, not aptitude nor achievement. It’s likely that this ability is highly heritable. The definition is clearly about the acquisition of knowledge. That's another way of saying learning. It's talking about thinking and reasoning and that's where the idea of problem solving is clearly coming in. The definition also specifies dealing adaptively and this is an important point because this is the sense in which intelligence is, in fact, multifaceted but it's also functional; it's adaptive, it serves a function. Finally, it includes the environment and that emphasises the importance of realising that this definition is in terms of culturally valued achievements. A question that arises is whether we can distinguish between academic intelligence and other forms of intelligence. We will return to that question in the next presentation.

{SLIDE 7} Now we turn to the history of how psychologists have gone about trying to develop tests to measure intelligence. Here, I have summarised the most important names in the early development of intelligence assessment. The first person I've included is Francis Galton who worked in London in the second half of the nineteenth century. His contribution was to attempt to isolate the biological basis for intelligence, which he argued was inherited. He adopted a laboratory approach to collect the necessary data. To measure mental abilities Galton relied heavily on physical measures, such as height, weight, strength, rate of movement, visual and auditory acuity and reaction times because he believed that there was a relationship between sensory and mental acuity. His ideas have proved to be very influential, particularly over the last 40-50 years. But at the time, his measures were too crude and the definition of intelligence not yet well developed, so there was little interest in his work. Another reason why interest moved away from Galton is that he had a contemporary working in France, Alfred Binet. The Minister of Education in France was concerned about identifying children with low school achievement who needed special attention and he wanted the distinction to be made objectively by means of testing so a teacher could not assign a child to a special school as a punishment. In this context, Binet and his collaborator Theodore Simon devised the first intelligence test to identify children who could not benefit from ordinary school instruction. The test, constructed by Binet and Simon, consisted of several subtests that sampled different mental abilities with an emphasis on tests of judgment because Binet felt that judgment was a key aspect of intelligence. He gave each test to many children and developed average scores for each age and sex. He then was able to say at what age level any individual child scored. This was called the child’s mental age. A German psychologist named William Stern took the concept of mental age another step. He divided mental age by actual chronological age. This resulted in an intelligence quotient score – the IQ score - that was the ratio of a child’s mental age divided by the child’s chronological age. Multiplying this ratio by 100 avoided fractions. For example, if a child was reading at the level of a 9 year old, the child’s mental age was 9. If this child actually had a chronological age of 9, the IQ would be 9 divided by 9 times 100, for an IQ of 100. If a child had a mental age of 10, but was only 9 years old, the IQ would be 111. The point of these early tests was to find children who were not doing so well in school relative to their peers, and get them special attention. The Binet-Simon test actually worked reasonably well for this purpose. However, one problem with the concept of mental age is that it is hard to assess after about age 16. Can we really see a mental age difference between a 19 year old and a 21 year old? The mental age of a 30 year old really isn’t much different than that of a 40 year old, so the Binet-Simon test was not really useful or intended for adults. Note that the IQ score is a measure of a child relative to his peers. The final name I’ll mention is Lewis Terman who was at Stanford University in the United States and he made the first English translation of the Binet-Simon test in 1916 and it became known as the Stanford-Binet, which is still in existence today. {SLIDE 8} What followed in the history of intelligence testing was largely a consequence of the entry of the United States into World War I in 1916. The army needed a quick and efficient means for streaming potential military recruits into the army. The problem with the new Stanford-Binet was that it was an individually administered test, requiring trained administrators and over an hour of testing. The army required a test that could efficiently administered to large groups of recruits. Robert Yerkes led the development of two tests, the Army Alpha and Army Beta designed to measure verbal ability, numerical ability, ability to follow directions, and general knowledge. The Alpha was for literate recruits and the Beta was for illiterate recruits and those who failed the Army Alpha. The overwhelming success of these tests, which, by the end of the war had been administered to nearly two million men, meant they provided the template for the subsequent development of intelligence tests – some of the items used in these tests still appear in modern tests. {SLIDE 9} David Wechsler was someone whose ideas about intelligence were again common sense intuitions. Wechsler believed that intelligence was made up of several different components that could be measured separately, although he also believed that, because these components were intercorrelated, intelligence also included a general, global capacity. The Wechsler scales were recognised as an improvement on the Stanford-Binet because they provided more than just a single IQ score, and assessment using them took account of what were termed “non-intellective” considerations, like confidence when test taking, motivation to score well, and paying attention to test instructions. He also introduced an improved scoring system that avoided problems associated with the fact that MA norms cannot be meaningfully applied to adults because MA development ceases for most young adults around 20 years of age. The modern Wechsler scales cover all ages across the lifespan from 4-90 years. Wechsler began to develop these tests in the late 1930s. His first versions distinguished verbal IQ (VIQ) from performance IQ (PIQ). The most recent fourth edition (released 2008) reflects later

research about different cognitive structures that comprise intelligence, like verbal, spatial and reasoning abilities, and memory and processing speed. {SLIDE 10} Following Wechsler, modern intelligence tests do not use anything like the ratio of mental age to chronological age (the origin of the terminology intelligence quotient, the IQ) to express scores on the tests. So while it is still common to refer to IQ, it is not a quotient. Rather, it is a deviation score. Here’s how deviation scores work. First, recall the normal distribution; IQ scores are normally distributed in large populations, and so are their subtest scores. The tests were developed so that this would be true. Each subtest is administered to a large, population representative sample of individuals. Scores are calculated for people at different ages; for children this will be in fine gradations – even months, whereas for adults it will a broader age range – say five years. These are the norm groups. Each norm group has a mean and standard deviation on each subtest. Each norm group will likely have a different average score on this test. For example, younger test takers may average 8 points if they are 10 years old, and older people taking the same test—say at age 12—might average a score of 14 points. This is why it’s important to have norm groups for each age. If a new 12 year old takes the subtest and scores 14, he is scoring at the average for his age. If he scores above or below 14, the deviation from the norm average can be calculated and his score can be expressed by how much it deviates from the normative mean. The average deviation across all the subtests is used to calculate the deviation IQ for the full battery. A score of one standard deviation above the mean ranks the person higher than 84 percent of the norm group. One standard deviation below the mean ranks the person at about the 16th percentile. Most modern IQ tests are normed so that they have a mean of 100 and a standard deviation of 15. You can see that IQ scores and their meaning depend on having good norms. This is one reason that new norms are generated periodically for these tests. {SLIDE 11-15} So what are the items on the WAIS like? One of the subtests is called General Information. Example questions would be: What is the capital of Brazil? Who were the Goths? Who is pictured on the $10 bill? What symbol is on the Canadian national flag? This would be a test of what is called crystallised intelligence. Another subtest is called Digit Span. The test administrator reads a series of digits, and when finished, you repeat the digits back in order. This test has two parts. In the first part, you repeat the digits in order as you heard them. In the second part, you repeat the digits back but in reverse order – this is a test of short-term or working memory. On the slide you see items that measure other abilities. This one measures mental speed and this one measures reasoning ability and finally this one measures visuospatial ability. Scores on all these tests are combined in various ways to give several domain scores and the overall score (called full scale IQ, FSIQ) is a measure of general intelligence.

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Intelligence

Professor Nick Burns [email protected]

Overview Presentation 1: Intelligence in historical context Presentation 2: The nature of intelligence Presentation 3: The measurement of intelligence Presentation 4: Heredity environment and intelligence Presentation 5: Extremes of intelligence

Learning Objectives •  Familiarity with early history of how intelligence has been defined, guided by implicit theory •  Familiarity with the related history of early attempts to assess intelligence •  Familiarity with content and structure of a successful set of tests – the Wechsler scales

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Implicit theories of intelligence •  Adaptation to novel situations •  Practical problem solving •  •  •  •  • 

Verbal expression and number ability Abstract reasoning Social competence Mental speed Learning and Memory

Definition of intelligence Intelligence is the ability to acquire knowledge, to think and reason effectively and to deal adaptively with the environment

Definition of intelligence Intelligence is the ability to acquire knowledge, to think and reason effectively and to deal adaptively with the environment

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Early history of intelligence testing •  Francis Galton (1822 - 1911) –  first attempt to measure intelligence

•  Alfred Binet (1857 - 1911) –  first test of mental age

•  William Stern (1871 - 1938) –  invented the intelligence quotient (IQ)

•  Lewis Terman (1877 - 1956) –  Stanford Binet first English translation

Army Alpha and Army Beta •  •  •  • 

Spoken directions Arithmetical problems Practical judgement Synonyms-antonyms

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Disarranged sentences Uncompleted series of numbers Analogies General knowledge

Wechsler’s tests of IQ David Wechsler (1896 -1981) •  WPPSI III – 

Wechsler Preschool Primary Scale of Intelligence

•  WISC IV –  Wechsler Intelligence Scale for Children •  WAIS IV –  Wechsler Adult Intelligence Scale •  Deviation IQ – 

relative rank within a specified age distribution!

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The distribution of IQ scores

The Wechsler Scales

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The Wechsler Scales

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Lecture 2 {SLIDE 1} This presentation has as its topic The Nature of Intelligence. In the first presentation, I talked about the work of Galton and of Binet; their influence continues to this day and, in effect, the two approaches to the nature of intelligence I am going to focus on trace their origins to these work of these two. We will first consider what is called the psychometric approach, which relies on a statistical technique called factor analysis to examine the structure of a set of mental tests in the tradition of Binet. Then we will consider an approach that is concerned with the cognitive processes that are required to demonstrate intelligence, this is the approach pioneered by Galton. {SLIDE 2} The learning objectives for this presentation are to know about the proposed structures of intellect found via using factor analysis. This work began in the very early 20th Century and gave rise to a debate that lasted most of that century. Three of the key figures in that debate were Charles Spearman, Louis Thurstone, and Raymond Cattell. Arguably, this debate was resolved in the 1990’s with the work of John Horn and John Carroll. The third objective is to know about the cognitive processes approach. Finally, I will introduce some broader ideas about intelligence that do not arise from either the psychometric or cognitive processes approaches. {SLIDE 3} The structure of intelligence refers to how performances on a set of different tests of mental abilities relate to each other. This approach operates on the differences between individuals in test performance and the pattern of correlations between scores on mental tests. The aim of factor analysis is to reduce the large number of correlations between tests scores to a smaller set of mental factors that are then assumed to underlie performance on the tests. {SLIDE 4} The psychometric approach begins with the work of Charles Spearman who was a Professor at University College in London. His famous paper on the nature of intelligence was published in 1904 and it was called ‘General Intelligence’ Objectively Determined and Measured. Spearman is credited with the invention of factor analysis. His theory of intelligence grew from his observation that all tests of mental ability are positively correlated with each other. He believed that this was because performance on all of the tests relied on a single general capacity – general intelligence, or g. Spearman also realised, however, that because correlations between tests of mental abilities were not perfect, that he needed to invoke other, specific, factors to fully explain test performance, he referred to these as s factors. So, if we had a test of vocabulary, for example, performance on the test would be largely determined by g but in order to fully explain differences on the test, we would have to take account of something that you might call verbal capacity. Spearman’s theory of intelligence, then, was a two-factor theory in that he thought test performance depended on two factors, one general, g, and one specific to a given test, s. Spearman’s theory can also be thought of as hierarchical in that g is important to all tests whereas s relates only to specific test performance. We will see shortly, that this notion of a hierarchical structure of intelligence is found in modern models of the structure of intelligence. {SLIDE 5} Louis Thurstone was an American contemporary of Spearman’s. He developed an alternative model to Spearman’s and this was the beginnings of the century long debate on the structure of intelligence that I referred to earlier. Thurstone looked beyond just...