Nutrition & Food Science

ISSN: 0034-6659

Article publication date: 1 February 1999



Wells, D. (1999), "Intelligence", Nutrition & Food Science, Vol. 99 No. 1.



Emerald Group Publishing Limited

Copyright © 1999, MCB UP Limited



Detterman and Sternberg in 1986 wrote to 24 theorists asking them to define intelligence. This was a repeat of a request carried out in 1921. Sternberg and Berg analysed the responses. A total of 25 attributes were mentioned but only three were mentioned by 25 per cent of the respondents. Obviously intelligence means different things to different people. It is perhaps better to consider intelligence not as a natural phenomenon (something pre-existing within people) but one created through social activities, a social construct, culturally and historically determined.

The conception of intelligence has interested people for thousands of years. For example Plato in 340 bc thought that intelligence was innate. He believed that intelligence was a characteristic of the leaders of society and that the general intelligence of society could be raised by eugenics. Aristotle thought teaching was the basis of intelligence and that intelligence was a common feature among all citizens of Greece whatever their social standing.

Francis Galton in the late nineteenth century carried out studies in an attempt to show that intelligence was due to nature. He believed that intelligence was the hallmark of different social classes and like Plato favoured eugenics. Galton thought that intelligence testing would improve the success of the eugenics programme for the improvement of society. He ignored the fact that high social status could come from the inheritance of wealth and privilege and also by personal effort.

Galton assumed that measures of sensory discrimination should be good tests of intelligence. In 1884, at a large exhibition in London, he tested 9,000 men and women who each paid 3d to have their mental abilities assessed. Galton tested their motor reaction times, visual and auditory discrimination and touch sensitivity. It was later discovered that sensory and motor tests did not correlate positively nor did they correlate with school examination results. There was also little or no relationship between test results and social status. In effect the tests were not an indication of intelligence. They remain notable, however, in being the first attempt to measure intelligence.

At the beginning of the twentieth century Alfred Binet attempted to measure the mental capacities of sub-normal children so their teaching could be made appropriate for their special needs. Binet believed that mental ability could be improved by mental exercises to improve attention, memory and judgement. He used the "brightness" of a sample of children in normal schools as the criteria of intelligence. The test he devised, known as the Simon-Binet test, had 54 items to identify a child's ability to follow instructions. Some of the tests for younger children were simple, such as naming the parts of the body and describing a picture. Other tests for the older children were slightly more complex such as finding rhymes for a given word and repeating a sentence with 26 syllables. The test was arranged in a series of groups in increasing order of difficulty each being judged to be appropriate for children of a certain age. Each child did as many of the groups as possible before they became too difficult.

Binet categorised the children he had tested by relating their mental age, as judged by their ability to give satisfactory results on the tests for children of a certain age, with their chronological age. Mental age divided by chronological age gave the mental quotient. This figure identified those children who needed special schooling. When this figure is multiplied by 100 it gives the intelligence quotient or IQ which is in customary use today.

Shortly after Binet devised his test it was used in a revised form in many other parts of the world. However, its use among people from widely different social and ethnic backgrounds gave cause for concern. The original test ignored factors such as background knowledge and cultural experience and was subsequently revised in 1916. Further revisions were made in 1937 and 1960 when a wider variety and greater number of test items were included. The tests were then known as the Stanford-Binet scales and were used to measure normal and superior intelligence as well as the subnormal.

Before 1960 the Stanford-Binet test was designed for young people up to the age of 16 but this was extended to 18 in the 1960 revision. The scale published in 1916 had better standardisation with the process of age grading items based on a larger representative sample. In the 1937 revision substantial extension and revision of the scales took place and they were standardised on nearly 3,200 people.

In 1938 Cyril Burt advised the Consultative Committee on Secondary Education that intelligence is a fixed and hereditary factor that is static throughout life and can be measured reliably by the age of 11 years. This led to the introduction of the 11+ exam in 1944 and determined whether children should go for their further education to a grammar school or to a secondary modern school. The exam was based on IQ tests but it was later criticised as it restricted children whose intellectual and scholastic ability improved after the age of 11 to inferior education. The exam also discriminated against children from under-privileged backgrounds and was abolished in the 1970s.

Ravens Progressive Matrices were introduced in 1938. This test was designed to be used with subjects irrespective of age, sex, ethnicity or education. The Mill Hill Vocabulary test was published in 1944 as a verbal companion to Ravens Progressive Matrices.

The psychometric approach to intelligence believes that intelligence is some underlying, all round strength which is characteristic of the individual and is domain general. It increases during childhood by the process of maturation which is an increase in intellectual competence but this is not a further development of intelligence. The emphasis is very much on the measurement of intelligence by IQ tests to compare and differentiate between individuals.

The cognitive approach to intelligence considers actual knowledge and reasoning power. This approach is based on the establishment of the entire cognition in terms of specific cognitive processes and reasoning power. It aims to define intelligence in terms of basic essential capacities and is domain specific.

More recent research into cognitive development has included the research by Sternberg and Gardner. Instead of considering intelligence as a basic unitary power, an information processing approach has attempted to define it in terms of specific cognitive processes. This approach sees intelligence as steps or processes people go through in solving problems. Sternberg 1984 has suggested that intelligence develops by increasing the efficiency of separate mental operations which he calls components. He identified several of these components: encoding or the representation of facts in memory; inference or the processes used in the actual solving of problems and also mapping, applying, evaluation and response. Sternberg's research has involved breaking down individual responses to IQ questions and comparing individuals' responses. Sternberg believes that people differ from one another not only in their overall level of intelligence but also in the way they think. One person may be judged more intelligent than another because they move through the same steps more quickly or efficiently. Alternatively they may be more familiar with the required problem solving steps. These processes illustrate how the information is represented internally and which components are used. It has, however, been criticised for reducing intelligence to a sequence of almost mechanical operations. How these work in the cognitive system is not clear.

Gardner's theory of multiple intelligence is based on the fact that intelligence is not a single unitary entity but a collection of multiple intelligences, each one a system in its own right. Each intelligence is independent of all the others but the different intelligences interact. Gardner believes that they are genetically determined and have evolved by natural selection. The different intelligences are also the result of some developmental processes and are influenced by educational and cultural factors. The different intelligences include linguistic, logical-mathematical, spatial, musical, bodily or kinaesthetic and personal intelligences.

Piaget studied intelligence as a process of adaptation to the environment and not a set of capabilities. He was not interested in the way individuals varied but rather in the stages all individuals go through. Piaget believed that intelligence does not arise from either the inside or the outside. The basic constituents of intelligence are co-ordinations which become represented in mental structures. For example, rolling a ball of clay shows that length and thickness are co-ordinated. Co-ordination also takes place between these dimensions and sensations in the muscles and joints of the hand that rolls the clay. We can also predict what would happen when the clay is rolled back into a ball i.e. reversibility. Co-ordinations lead to increases in intelligence about the world by increasing our predicitve abilities. Once cognitive structures have developed, individuals discover further concepts on their own.

More recent intelligence tests have tested multiple intelligences. The American psychologist David Wechsler devised a test for adults of 16 and over in 1939, the Wechsler Adult Intelligence Scale. It aimed to discover verbal IQ, performance IQ and full scale IQ. This was not because Wechsler thought they represented different kinds of intelligence but to discover how an individual's assets or shortcomings may influence his overall functioning. In 1949 a Wechsler Intelligence Scale for children from 6 to 16 years was introduced and this was revised in 1974 and 1992. A Wechsler Pre-school Primary Scale of Intelligence has also been introduced.

British Ability Scales, first introduced in 1979, provided a set of 23 subscales testing verbal IQ, visual IQ and general IQ. The tests were standardised on a British population and are thought to measure a wider diversity of mental abilities than the Wechsler scales. The British Ability Scales are designed for use with children and adolescents up to the age of 18.

Is the idea of an underlying single ability now of historic interest only? I believe that it is. The more recent intelligence tests aim to find the difference between varying abilities, such as verbal, visual and general IQ. The Wechsler sub-test involves assessment of digit span, vocabulary, arithmetic, comprehension and similarities, all different mental abilities. Many people know of brilliant scientists who are unable to answer everyday, commonplace questions and expert media persons who almost boast of knowing "nothing about maths".

There are also cases of well known child prodigies in subjects such as music and mathematics who show less than average competence in other subjects. So-called idiot savants may have a low IQ yet show remarkable talents in one particular field. One case in point was a woman who had an IQ of 73 who was a brilliant pianist. Autistic children often show islets of ability in one particular field yet have a low IQ. The obvious example here is Stephen Wiltshire who produces remarkable architectural drawings.

These examples show that complex intellectual skills can exist in relative isolation thus supporting Gardner's theory of multiple intelligences.

Dilys Wells

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