The concept of intelligence tests began with the work of Francis Galton in the late 19th century. Galton believed that measurement of intelligence was to be as direct as possible and hence suggested reaction time as a feasible approach (Chamorro-Premuzic, 2005). He used various sensori-motor measurements and it is interesting to note that modern day psychologists such as Arthur Jensen and Mike Andersen are working on similar lines.
Intelligence testing began in France in 1904 when psychologist Alfred Binet was asked by the French Government to find a method of differentiating between normal children and intellectually inferior children so that the latter could be put in special schools. The Binet scale (also known as the Binet-Simon scale) was developed in 1905. German psychologist L. Wilhelm Stern was the first to coin the term “intelligence quotient” (IQ), a figure derived from the ratio of mental age to chronological age. Binet warned that his instrument was not to be used as a general device for measuring intelligence.
According to Binet, “the scale, properly speaking, does not permit the measure of intelligence, because intellectual qualities are not superposable, and therefore cannot be measured as linear surfaces are measured. ” Binet feared that IQ measurement would be used to condemn a child to a permanent “condition” of stupidity, this negatively affecting his or her education and livelihood. H. H. Goddard, director of research at Vineland Training School in New Jersey, translated Binet’s work into English and used it for admission purposes in his school.
He classified people as being normal, idiots, or imbeciles and even developed a new word “morons,” to describe people who were somewhere between normal and idiots. Unlike Binet, Goddard considered intelligence a solitary, fixed and inborn entity that could be measured (Chamorro-Premuzic, 2005). Lewis M. Terman revised the Simon-Binet Scale and his final product launched in 1916 was the Stanford Revision of the Binet – Simon scale of Intelligence or Stanford- Binet. Terman also changed the concept of a mental age into a standardized IQ score, which is the approach still used today.
This became the standard intelligence test in the United States for the next several decades. Goddard’s believed firmly in the innateness and inalterability of intelligence levels so much he lobbied for restrictive immigration laws and allow only immigrants of superior intelligence into the United States. Charles Spearman (1927) argued that, as a rule, people who do well on some intelligence tests also do well on a variety of intellectual tasks such as 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; and Special Abilities: which were required for performance on just one kind of mental test. The concept of a general intellectual capacity was his major theme (Chamorro-Premuzic, 2005). Another test designer was David Wechsler.
Wechsler designed an instrument for measuring intelligence by measuring both verbal and nonverbal abilities. The original Weschsler-Bellevue test in 1939 was used in civilian and military applications. In 1949, Wechsler produced the Wechsler Intelligence Scale for Children (WISC) and in 1955 he produced a revision of the adult scales named the Wechsler Adult Intelligence Scale (WAIS). Revised versions of these scales are used till today (Intelligence, 2005). Thurstone (1938) identified 7 ‘primary mental abilities’ which he judged to be more important.
These were: verbal comprehension, word fluency, number, space, associative memory, perceptual speed and reasoning (Intelligence, 2005). This was the first multi-factor approach to intelligence. Thurstone’s tests have become extinct mainly because they were not able to predict academic or occupational performance. Raymond Cattell (1963) suggested that there are two related but distinct components of g: fluid and crystallized intelligence. Fluid intelligence is the ability to see relationships whereas crystallized intelligence is acquired knowledge and skills.
Fluid intelligence decreases with age and crystallized intelligence increases with age. Guilford denied the existence of any general factor at all. Instead, he proposed that intelligence comprises 180 elementary abilities that are composed of a combination of three dimensions: operations: what a person does (6-types); contents: the material on which operations are performed (5-types) and products: the form in which the information is stored and processes (6-types) (Intelligence, 2005).
The most widely accepted factorial description of intelligence is a hierarchical one, e. g. Vernon and Carroll. Vernon accepted that both Spearman (single g factor) and Thurstone (multiple primary mental abilities) were right. He suggested that intelligence can be described as comprising abilities at varying levels of generality with g as the highest level and major group factors at the next level. Howard Gardner (1983) argues that there are seven different types of intelligence that are independent of one another: verbal, mathematical, musical, spatial, kinaesthetic, interpersonal (social skills) and intrapersonal (self-understanding) functioning.
Today, the most popular intelligence tests are the Stanford-Binet, the Wechsler Intelligence Scale for Children (WISC), the Wechsler Adult Intelligence Scale (WAIS), and the Kaufman Assessment Battery for Children (Kaufman-ABC). Significance to Teaching/Learning Process: Intelligence is often seen as synonymous with learning ability (Jensen, 1989). This is because of two reasons: IQ test scores (a measure of general intelligence) correlate in complex ways with measures of learning. Second, researchers have different concepts regarding intelligence.
Charles Spearman (1904; 1927) proposed that there is a largely innate general ability (called g) that is distributed unequally in humans. G is the ability to reason and to educe (draw out) correlates. It is the ability to abstract, to see similarities and differences, and to extrapolate trends. The major rationale of most traditional IQ tests is that they tap g by assembling a variety of mental tasks. Outstanding achievers need a high g level. There is evidence that g exists. On average, persons who do well on one task do well on all, and those who do badly on one do badly on all.
A factor analysis of the data typically reveals a general factor that aids performance on all tasks. A lot of research has investigated the IQ-learning link. According to Jensen (1989) IQ has little or no effect on relatively simple types of learning, such as classical conditioning and rote learning, except in very low scorers. IQ effects are strong when learning is intentional, the task is of moderate difficulty and complexity, the task is of meaningful information, and learning is helped by transfer from related past learning (Howard, 1995).
Early work found little effect of IQ on learning simple motor skills (Ferretti and Butterfield, 1992). However, later studies suggest that IQ has a big impact in the early stages of skill learning and progressively less as task performance becomes more automated. Ackerman (1987; 1988) presented supporting data and the following theory to explain this finding: Initially, IQ and abilities specific to the task (such as spatial and verbal abilities) are important because higher scorers can better devise new procedures to do the task and may better and more rapidly work out novel task requirements.
In the second phase of skill learning, as performance becomes more automatic, the effect of IQ decreases and that of perceptual speed increases. In the third phase, when performance is largely automated, psychomotor ability differences then have most impact. Even so, individuals eventually converge on the same performance level, given enough practice. This implies that almost anyone may become an expert with enough practice (Howard, 1995). People differ in their general preferences for using certain types of strategy, in their learning processes (Scheck, 1988).
These preferences are called cognitive and learning styles. Cognitive style is seen as a general, habitual way of processing information, whereas a learning style is a preferred way of acquiring knowledge. It is now believed that basic cognitive processes, such as inspection time, may account for approximately 20% of the variance in an IQ test. Both Binet and Spearman, pioneers in the psychological study of intelligence, believed that there was a strong hereditary basis for individual differences in intellectual ability; however, they also acknowledged the influence of sociocultural (i.e. , environmental) factors on the development of specific skills.
Thus, although individuals with the same education may differ in ability due to biological causes, two individuals with the same IQ may experience different intellectual developments if exposed to unequal—in particular, opposite—training or environments. This debate has affected the reputation of IQ tests and even differential psychology. There has been evidence both in favor and against the hypothesis that intelligence can be inherited, and this ambiguity has probably increased the debate.
Piaget (1952; Piaget & Inhelder, 1969) identified various developmental stages in the evolution of adult intellect and his theory of intellectual development is based on four universal stages—namely, sensorimotor, preoperational, operational and formal operational (Howard, 1995). The essence of Piaget’s (1952) theory is that there is a universal interaction between biological and environmental variables that accounts for the progressive development of adult human intelligence. Therefore, this theory explains the passage from basic sensorial and motor skills (at the age of 2 years) to very abstract (formal/logical) mental operations.
It has been argued that individual differences in IQ scores should be conceptualized in terms of multiple intelligences, rather than a single, general intelligence because individuals may be good at some, but bad at other, ability tests. This idea has gained support in the last two decades, but was most emphatically defended by Guilford (Howard, 1995). Impact on Society: 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 was found to have limitations and hence, Robert Yerkes, a psychologist and army major, assembled a staff of 40 psychologists including Terman to develop group intelligence tests. This resulted in the Army Alpha and Army Beta tests. After the war, industry, business and education saw potential value of psychological testing (Lemann, 1995). Broad-scale testing in America was intended to be two things at once: a system for selecting an elite and a way of providing universal opportunity. The second purpose generates the public consent that supports the first.
Admissions to universities require the applicants to take the SAT test (Lemann, 1995). Recruitment to top firms needed the applicants to pass basic IQ tests. Finally, the government ensured that recruitment to the Army was based on IQ tests and during a certain period, it even ensured that immigrants should take the IQ test. Congress passed laws severely restricting immigration in 1921 and 1924, with the result that people stopped worrying that the country was being flooded by the mentally inferior (Lemann, 1995).
In the April, 1948, issue of a publication called The Scientific Monthly an article appeared under the title “The Measurement of Mental Systems (Can Intelligence Be Measured? ). ” The authors, W. Allison Davis and Robert J. Havighurst, believed that intelligence tests were a fraud and served to label the fortunate children of the middle and upper-middle classes as scientifically superior. This created a controversial situation regarding IQ tests (Lemann, 1995).