History & Development of Intelligence & Testing

History & Development of Intelligence & Testing

1. Francis Galton: The 1st Modern Attempt (late 1800s)

Intelligence tests are grounded in the work of Francis Galton in the late 19th century. Galton is considered to be the father of the study of individual differences. For Galton, measurement of intelligence was to be as direct as possible a measure of underlying intelligence. Hence, Galton suggested reaction tiame as a feasible approach and pursued various sensori-motor measurements..

Interestingly, more contemporary "Galton-like" approaches are being pursued by psychologists such as Arthur Jensen and Mike Andersen who assert that they are assessing the integrity of the central nervous system - inherent capabilities (Intelligence A) - as opposed to manifestations of intelligence in everyday life (Intelligence B).

2. Alfred Binet: The origins of IQ Testing (early 1900s)

Alfred Binet is celebrated in history as the man who created the first 'intelligence test' in the form as we know them today. He is commonly known as the father of IQ testing. In 1904, Binet was commissioned by the French Ministry of Public Instruction to develop techniques for identifying primary grade children whose lack of success in normal classrooms suggested the need for some form of special education (Gould, 1981). In 1905 he produced the Binet-Simon scale [with Theodore Simon] - the first intelligence test. Binet took a pragmatic approach, choosing a series of 30 short tasks related to everyday problems of life

3 & 4. Terman (1916) and Stern (1912)

Lewis Terman (1877-1956) of Stanford University in the US decided to use Binet's test. He found that the Paris-developed age norms didn't work very well for Californian school children. So he revised the test: adapted some items, added other items, established new age norms, and extended the upper age limit to "superior adults". This became the Stanford-Binet revision in 1916. In this revision the Intelligence quotient first appeared. To arrive at an IQ score, Terman relied on a formula expressing the relation between an individuals mental age and chronological age developed in 1912 in Germany by Wilhelm Stern: 1912 Wilhelm Stern proposed the following formula:

IQ = mental age x 100/chronological age

 

5. Yerkes: Army Tests (WWI)

The US army at the beginning of WWI was faced with the problem of assessing the intelligence of great numbers of recruits in order to screen, classify, and assign them to suitable tasks. The Stanford-Binet test required a highly trained person for individual administration - thus it would prove time consuming and costly for large-scale use.

So, when the US entered WWI in 1917 a committee was appointed by the APA to consider ways that psychology might assist the conduct of the war. Head of this committee was Robert Yerkes. His brief was to develop group intelligence testing.

Robert Yerkes, a psychologist and army major, assembled a staff of 40 psychologists [including Terman] to develop a group intelligence test. This resulted in the Army Alpha and Army Beta tests. The Beta was a version of the Alpha specifically for use with non-English-speaking and illiterate persons. [Instructions to those taking the Beta were given by demonstration or pantomime, rather than orally or in writing.]

6. Charles Spearman: (1920s)

Charles Spearman (1927) analysed the relations among experimental intelligence tests using 'factor analysis'. He argued that, as a rule, people who do well on some intelligence tests also do well on a variety of intellectual tasks [vocabulary and mathematical and spatial abilities]. And if people did poorly on an intelligence test, then they also tended to do poorly on other intellectual tests. That is, he observed correlations among performance on a variety of intellectual tasks.

Thus, he proposed, a 'two-factor' theory of intelligence:

-  General Ability (g): which was required for performance of mental tests of all kinds; he called this a kind of 'mental energy' that underlies the specific factors

-  Special Abilities: which were required for performance on just one kind of mental test.

e.g. Scores on a verbal comprehension test are largely determined by ones level of general intelligence but they are also affected by ones specific ability to perform verbal comprehension tasks.

7. Weschler: Intelligence Scales for Adults and Children (1939 - present)

Another test designer was David Wechsler. Wechsler felt that the Binet scales were too verbally loaded for use with adults, so he designed an instrument with sub-tests to measure both verbal and nonverbal abilities, largely borrowing from many other tests, such as the US Army Alpha test. He adopted a mean score of 100, since the Stanford-Binet metric had become universally accepted. The original Weschsler-Bellevue test in 1939 proved quite successful in civilian and military applications.

a. In 1949, Wechsler produced the Wechsler Intelligence Scale for Children (WISC), which competed with the Stanford-Binet test.

b. In 1955, he produced a revision of the adult scales named the Wechsler Adult Intelligence Scale (WAIS). And later he produced a scale which could be used with pre-primary children. These scales have all been revised, but still show a distinct resemblance to the original 1939 scale.

8. Thurstone: Primary Mental Abilities (1930s)

Another 'factor analyst', Thurstone (1938), accepted Spearman's hypothesis of a general factor. But he disputed its importance. He argued that g is in fact a second order factor or phenomenon

-   one which arises only because the primary or 'first-order' factors are related to one another. Thus, Thurstone identified 7 'primary mental abilities' which he judged to be more important. These were:

1.Verbal Comprehension: vocabulary, reading, comprehension, verbal analogies, etc.

2.  Word fluency: the ability to quickly generate and manipulate a large number of words with specific characteristics, as in anagrams or rhyming tests

3.  Number: the ability to quickly and accurately carry out mathematical operations

4.  Space: spatial visualizations as well as ability to mentally transform spatial figures

5.  Associative Memory: rote memory

6.  Perceptual Speed: quickness in perceiving visual details, anomalies, similarities, etc.

7.  Reasoning: skill in a variety of inductive, deductive, and arithmetic reasoning tasks

So, Thurstone's approach constituted the first multi-factor approach to intelligence.

Thurstone's tests have largely dropped out of use because the hope that they would be able to more accurately predict academic or occupational performance than general intelligence was not fulfilled.

9. Raymond Cattell: Fluid & Crystallised Intelligence (1960s)

Raymond Cattell (1963) [not to be confused with James McKeen Cattell, a contemporary of Galton's who was also significantly involved in early attempts at psychological measurement] suggested that there are two related but distinct components of g: fluid and crystallised intelligence.

Fluid: ability to see relationships, as in analogies and letter and number series = primary reasoning ability

Crystallised: acquired knowledge and skills = factual knowledge

Fluid intelligence decreases with age and crystallised intelligence increases with age. Thus mathematicians and scientists, who need fluid intelligence, produce their best work in thier 20s and 30s; whereas those in the field of history, philosophy and literature produce their best work in their 40s, 50s and beyond as they have accumulated more knowledge. Interestingly, poets, who depend more on fluid than crystallised intelligence, produce their best work earlier than prose authors: this has been observed in all cultures, languages and throughout history.

10. Guilford: many, many factors! (1960s - present)

Guilford (1967; 1988) parted company from the majority of factorial theorists by refusing to acknowledge the existence of any general factor at all. Instead, he proposed that intelligence comprises 180 elementary abilities. The 180 elementary abilities are made up of a combination of three dimensions which he calls:

-  operations: what a person does (6-types)

-  contents: the material on which operations are performed (5-types)

-  products: the form in which the information is stored and processes (6-types).

Guilford proposed that each combination of a specific operation, a specific type of content and a specific type of product defines a unique type of intelligence (6x5x6 = 180). In later versions of his theory he proposed even more types of intelligence.

Due largely to the practical implications of such a model, Guilford's theory has not significantly influenced psychological testing of intelligence.

11 & 12. Vernon & Carroll: Hierarchical Approaches (1960s - present)

Probably the most widely accepted factorial description of intelligence is a hierarchical one, e.g. Vernon (1960, 1965, 1971) and Carroll (1993). Vernon accepted, in a sense, that both Spearman (single g factor) and Thurstone (multiple primary mental abilities) were right. Vernon suggested that intelligence can be described as comprising abilities at varying levels of generality:

a. - at the highest level of generality (i.e. top of the hierarchy) is g as defined by Spearman);

b. - at the next level are 'major group' factors, such as:- verbal-educational ability [the kind of ability needed for successful performance in courses such as English, history, and social studies] and practical-mechanical ability [the kind of ability needed successful performance in courses such as draughtsmanship and car mechanics];

c. - at the next level are 'minor group' factors, which can obtained by subdividing the major group factors;

d. - and at the lowest (the bottom of the hierarchy) are specific factors again of the kind identified by Spearman.

13. Howard Gardner: Multiple intelligences (1980s to the present)

Howard Gardner (1983; 1993) supports Thurstones notion that intelligence comes in different packages. The most widely cited version of Gardners concept of intelligence is that there are seven different types of intelligence. Gardner has played around with this number and suggested a possible one or two more or even (in 1999) the possibility of a smaller number of intelligences.

He argues that the seven intelligences are: verbal, mathematical, musical, spatial, kinaesthetic, interpersonal (social skills) and intrapersonal (self-understanding) functioning. He argues that these different intelligences are independent of one another. Critics argue: not all these things are intelligence.

14. Robert Sternberg (1970s to present)

Robert  Sternberg (1977,  1985)  together  with  his  colleague  Richard  Wagner  (1993,  1995)

argues that there are three intelligences:

·         Academic

·         Practical

·         Creative

Sternberg and Wagner have designed a test of practical intelligence.