The Development Of Theories About Intelligence

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Introduction

Ideas about the nature of intelligence, its characteristics and whether it is inherited and fixed or subject to change, were developed throughout the twentieth century. Interest in intelligence began with the work of Darwin in the middle of the nineteenth century and the theories that emerged were not to be seriously challenged until the publication of Howard Gardner’s book Frames of Mind in 1983.

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Key Figures In The Development Of Theories Of Intelligence

Francis Galton (1822-1911)

The work of Charles Darwin on evolution led to widespread interest among scientists of the day about the nature of intellect. Darwin’s cousin, Francis Galton, followed up this interest by studying the lives of a range of eminent or successful people. Galton’s conclusion was that intelligence was inherited and that, across the population, intelligence could be seen to follow a pattern of natural distribution. This is sometimes described as a bell curve and simply means that most of the population will have levels of intelligence around the average score, while small numbers of people will have either very high or very low intelligence scores. It is this theory of distribution that has given rise to the use of terms such as percentiles and standard deviations. These are used not only to describe intelligence but also, for example, to compare individual babies’ weights to average weights.

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Galton went on to develop this theory by gathering a large amount of data. This in turn led him to pioneer the use of mental tests which (in these early stages of thinking about intelligence) measured reaction times and fine sensory discrimination ([34]). He discovered the phenomenon, now termed ‘regression to the mean’. This means that, for example, particularly tall, or short, or intelligent parents tend to have children whose characteristics are closer to average. Galton also favoured eugenics, which seeks to improve on human nature by selective breeding. He did not believe that everyone is born equal and wanted to improve on nature.

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Key Dates

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Alfred Binet (1857-1911)

Although born in Nice in Southern France, from the age of 15 Binet lived and worked in Paris. Originally studying law and medicine, he eventually took up natural sciences and psychology, which was at that time a new subject. Like Freud, Binet spent some time studying with Charcot, renowned for his work on hypnosis. Following the births of his two daughters in 1885 and 1887, Binet began to maintain a diary of observations of their behaviour and development. This was not unusual at this time – indeed there was what is sometimes known as The Child Study Movement ([35]). In 1877, Charles Darwin published his observations of his son Doddy. During the twentieth century this tradition was notably carried on by Jean Piaget (see How Children Learn page 37). What was particularly interesting about Binet’s baby biographies ([36]) was the fact that he did not just observe but tried out some simple experiments. In the process of reflecting on and analysing what his children did, Binet appears to have developed ideas about intelligence and how to measure it. He also developed some work on the conservation of number which was an aspect of development later given prominence by Piaget. Perhaps we should not be surprised about this – although Binet himself did not work with Piaget, his colleague Simon (with whom he developed intelligence tests) did.

Although Galton had started to devise some measures of intelligence, Alfred Binet is generally credited with developing the first real intelligence tests ([37]). Binet believed that the tests being developed on sensory responses by Galton were too simple and that more complex tests were needed. He explored the more complex notions of ‘comprehension, judgment, reasoning and invention’ ([38]). Over time he added a number of practical tasks drawing on children’s day-to-day knowledge. Binet had been approached in 1900 by the Parisian authorities and asked to devise a test which would determine whether or not children were sufficiently intelligent to benefit from school attendance.

In 1905 Binet, with his colleague Theodore Simon devised a series of such tests, geared to identifying children who would be unable to cope with mainstream schooling and would therefore need some form of remedial education. These were known as the Simon-Binet tests. The idea that children could be helped and that intelligence could be developed is not one which Galton had held – but it was central to the work of Binet. Binet argued that the scores arrived at through testing should not be seen as wholly accurate since the brain can reorganise or regenerate itself.

Binet himself was undoubtedly influenced by the earlier work of Itard (1775- 1838) and Seguin (1812–1880), both of whom had worked with children labelled by many at that time as ineducable. Their work was also to have a great influence on Maria Montessori (see How Children Learn pages 29–31) when she worked with what were then known as ‘retarded’ children in Rome.

The tests which Binet and Simon devised were said to have three roots. Some of the tests relied on medical information – what they themselves referred to as ‘the anatomical, physiological, and pathological signs of inferior intelligence’. Other tests were said to rely on pedagogy or what had been taught and learnt. The third group – which Binet regarded as the most important – focused on psychological aspects of behaviour such as reasoning.

Sample Test Items From Binet And Simon’s Measuring Scale Of intelligence 1911

The below examples set out some of the tests, graded according to age, devised by Alfred Binet and his colleague Theodore Simon ([39]):

Charles Spearman (1863-1945)

Spearman began his career in the army, but in 1897 after fifteen years he went to Germany to study experimental psychology with one of the pioneering figures in psychology, Wilhelm Wundt. By the time he received his degree he had already published a seminal paper on the factor analysis of intelligence (1904). Spearman subsequently moved to London University and in 1928 became Professor of Psychology when a separate Department of Psychology was created. He was strongly influenced by the work of Francis Galton and like him was particulary interested in the correlation between intelligence and other characterisitcs of people.

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A child scoring at 3 years 6 months on an intelligence test at the age of 3 years 9 months would be said to have an IQ of 93. An average score (where the test score or mental age is the same as the real age) would be 100. In this case the child is scoring slightly below their chronological age.

3.5 ÷ 3.75 x 100 = 93.33

A five year old child scoring at the level of a seven year old would be said to have an IQ of 140, which would be considered to be the mark of a gifted child.

7 ÷ 5 x 100 = 140

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Wilhelm Stern (1871-1938)

In 1912, Stern invented the term intelligence quotient, nowadays usually referred to simply as IQ. It is a figure which is arrived at by calculating a person’s mental age or intelligence test score and dividing it by their actual (or chronological) age. This number is then multiplied by 100.

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Edward Thorndike (1874-1949)

The work of the American, Edward Thorndike, as a behavioural psychologist has been very briefly outlined in How Children Learn (page 42). His interest in problem-solving was linked to an interest in the measurement of intelligence. In 1927 he published a book entitled The Measurement of Intelligence. In his view most intelligence tests were only focused on abstract intelligence. He believed that both mechanical intelligence (the ability to understand how the physical world works) and social intelligence (the ability to deal with other people successfully) were equally important. In addition he argued that in considering abstract intelligence, tests should take account of four dimensions – namely the difficulty and variety of tasks offered as well as their scope or area and the speed with which they were completed.

Thorndike was also interested in what he termed connectionism. Referring to the neural connections developed in the brain, he suggested that higher levels of intelligence made it possible for more bonds to be formed more easily. Thus he suggested those of lower ability would have greater difficulty in making connections. He, like Galton working half a century before him, believed that this ability was largely inherited – although he did think that the content of the thinking and making connections depended on experience. This view has many important echoes in work on the brain in the twenty-first century, particularly amongst those studying creativity.

Lewis Terman (1877-1956)

Terman’s name is widely associated with a range of intelligence tests. Building on Stern’s ideas about the measurement of IQ, he released in 1916 the ‘Stanford Revision of the Binet-Simon Scale’ or the ‘Stanford-Binet’ for short, drawing the name from the university at which he was then employed. During the course of the First World War, Terman developed widespread testing on American soldiers in an effort to place men in the roles best suited to their IQ.

In the early 1920s, an influential journalist, Walter Lippmann, criticised Terman’s use of IQ testing, which seemed to indicate that the average mental age of American adults was 14 years. In 1922, Terman is said to have suggested that nothing is of more importance than IQ. Lippmann responded quickly with a series of critical essays. He was among the first to draw attention to the possible cultural bias of IQ tests and to the social inequalities which they underlined.

In 1927 he further revised the Stanford-Binet tests, developing a version which became known as the Terman and Merrill tests. These tests took their name from the co-director of the project, Maude Merrill.

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Cyril Burt (1883-1971)

Burt was strongly influenced by Galton’s theory of intelligence. He, like Galton, firmly believed that intelligence is inherited. In fact, he stated that 80% of intelligence is inherited and not therefore subject to change ([40]). It is sometimes claimed that it was Burt who developed the first written IQ tests. His tests were developed for schoolchildren, unlike Terman’s initial work which focused on developing tests for categorising soldiers. Burt’s tests were designed to be used by classroom teachers in order to help them to identify both the children who, it was deemed, would not benefit from ordinary schooling and those who were gifted. He contributed to the writing of the 1944 Education Act which introduced the 11+ exam, which relied heavily on intelligence testing.

Although Burt was for a long time highly influential and was regarded as having considerable skills in academic, practical and political fields of work, his work has now been discredited. His most famous work was based on the study of a large number of identical twins separated at birth and reared in contrasting situations. It was claimed that this study proved that intelligence was inherited and not due to upbringing. The study was accepted and influenced views of intelligence for some considerable time.

Five years after his death, however, it was discovered that the data from this work had been falsified. He had not only made up data to support his own views, but had invented researchers. This was a shocking discovery that underlines many of the central debates around intelligence. For those, like Burt, who believe that intelligence is mainly inherited, it is perhaps important to ensure that money and time are not wasted on trying to develop children in ways which will not change their nature. Many others now believe of course that intelligence tests do not measure inherited factors, but reflect causal factors such as poverty, social class or ethnicity. For those who believe that intelligence is nurtured, it is vitally important for the well-being of individuals and nations to ensure that opportunities are broadened and high quality education safeguarded for all.

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Mystery Of Rising Scores: The Flynn Effect

It has been noted over many years since intelligence testing began that test scores have been rising. This would suggest either that people are becoming more intelligent or that what is being measured is not actually intelligence, but abstract problem-solving skills. These effects are seen particularly strongly in the lowest achieving groups in society, but overall it is suggested that, taking the population as a whole, the average IQ has been gaining about 3 points every ten years.

There have been several suggested reasons for this which may include:

Of course no one knows for sure what the real cause is – or perhaps it is a combination of these elements. ([41])

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Florence Goodenough (1886-1959)

Goodenough studied with Terman. She worked with children until she became a professor in the 1940s. She devised the Goodenough Draw-a-Man test (now generally known as the draw-a-person test). The test is very simple, children simply being asked to draw a person. Their drawing is then given a score which is based on the number of features they have included. Despite some criticisms – largely based on whether or not the tests actually measure intelligence – the test remains very popular. In addition to its use with children, the test (with various scoring schemes) is widely used in medical circles to test, for example, adult stroke patients or those with a range of psychological disturbances. It is simple to administer but is probably only useful as part of a battery of tests.

David Wechsler (1896-1981)

Wechsler devised intelligence tests which today remain amongst the most widely used. He defined intelligence as ‘the global capacity to act purposefully, to think rationally and to deal effectively with one’s environment’ ([42]). In 1939 he developed an intelligence test for adults, which was followed ten years later by a test for children. The preschool and primary test (known as WPPSI) was originally developed in 1967. It is regularly revised to take account of the Flynn effect (see box). The Wechsler Preschool and Primary Scale of Intelligence ([43]) uses the following tests:

Joy Paul Guilford (1897-1987)

In 1904, Spearman suggested a two-factor model of intelligence, namely general intelligence which is involved in all tasks, and specific individual abilities that make a person more skilled at one task than another.

In 1967 Guilford refuted this idea as being too simple to explain human intelligence. Guilford offered a cube as a model for his view of intelligence. This provides 120 elements which make up the intellect. The dimensions of the cube (length, breadth and height) are described as operations (or general intellectual processes); content (or broad areas of information) and product (the result of applying particular operations to specific content).

Guilford’s Cube As A Model Of Intelligence

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34 Gardner, H. et al (1996) Intelligence: multiple perspectives. London: Harcourt Brace College Publishers

35 Bartholomew, L. & Bruce, T. (1993) Getting to Know You. London: Hodder and Stoughton

36 Bergin, D. & Cizek, G. (2001) ‘Alfred Binet’ In Palmer, J. (ed) Fifty Major Thinkers on Education. London: Routledge

37 Gardner, H. (1999) Intelligence Reframed. New York: Basic Books

38 Gardner, H. et al (1996) Intelligence: multiple perspectives. London: Harcourt Brace College Publishers (page 47 citing Binet and Simon 1916)

39 Gardner, H. et al (1996) Intelligence: multiple perspectives. London: Harcourt Brace College Publishers (page 49)

40 Ridgway, J. (2001) ‘Cyril Lodovic Burt’ In Palmer, J. (ed) Fifty Major Thinkers on Education.London: Routledge

41 Neisser, U. (1997) ‘Rising Scores on Intelligence Tests’. American Scientist 85: 440-447

42 Kaplan, R. and Saccuzzo, D. (2004) Psychological testing:principles, applications and issues. (6th ed) Wadsworth (page 256)

43 based on http://en.wikipedia.org/wiki/Wechsler_Preschool_and_Primary_Scale_of_Intelligence