Higher Order Mental Processes as a Measure of Intelligence
It was originally believed that higher order mental processes, such as thinking and reasoning, could not be measured or studied empirically. As a result, intelligence testing was primarily conducted through physical attributes and reaction times. However, after studying the developmental processes of their own children, two pioneers in psychology, Alfred Binet and Jean Piaget, discovered techniques to understand and measure intelligence through higher and more complex functions, such as language abilities and abstract thinking. Both stressed the importance of understanding the developmental process in children as key to fully understanding adult intelligence. Others built upon the theories of these individuals to develop and refine standardized measures of intelligence.
Alfred Binet(1857-1911)  
Binet, originally a proponent of craniometry, began to doubt the favored method after conducting a number of his own experiments on young school children with great variability in head size and conflicting results. The differences among the higher and lower functioning students were negligible and failed to support to the craniometry theory. He decided to abandon this technique in favor of more psychologically sound methods of measurement.

Using the model developed by Galton, Binet administered reaction time experiments with his two daughters, Madeleine and Alice. He was surprised to find that, when the girls were paying attention to the stimuli, their reaction times paralled that of adults. Since the supposed "undeveloped intellects" of these young children matched that of mature adults, Binet questioned the utility of Galton’s procedures, suggesting that perhaps tests involving more complex functioning, such as language, would be more appropriate measures of intelliegence.


In 1904, after the passage of universal education laws in France, Binet was commissioned by the French government to develop a method to identify "subnormal" (or mentally "retarded") children that were in need of special education. With the assistance of Theodore Simon (1873-1961), a young physician, Binet set out to develop a series of tests for this purpose. In an effort to avoid confusing the lack of intelligence with a lack of formal schooling, the two avoided tests of specific school-related skills. Over several years, the Binet-Simon tests were refined for various age groups and included measures on a number of subject areas, including attention, memory, visual-motor tasks, similarities between various items, social judgment, and logical absurdities. Age was used as a discriminator, since normal children typically learned certain skills at a younger age than subnormal children. This significant indictor marked the beginning of age standardization in a genuine "scale" of intellectual ability. An actual score resulted from the scale by comparing "mental age" as scored on the test to the child’s chronological age; if the mental age was lower than chronological age by 2 or more years, it was suggested that the child was mentally "retarded" (a termed coined by Binet).

Binet, recognizing the reliance of a single score to apply meaning to a complex quality, cautioned against misusing these tests to inappropriately label children as mentally deficient. He realized the importance of individual motivation and culture for valid testing, and noted that intelligence is something that develops over time, with variability across individuals.

For more on Binet, click here!

Lev Semyonovich Vygotsky(1896-1934)
Vygotsky was a Russian psychologist who influenced the modern constructivist thinking with his Socialcultural Theory. Vygotsky believed that all higher mental functioning originated form the social environment.His theory has beeninfluential in understanding language development as well as the development of other theories such as Scaffolding (i.e., parents provide children with stimulation/new information that slightly challenges their developmental stage. As the child grows, new information/stimulation is provide based on their developmental gains.)
Jean Piaget(1896-1980) 
"Older children do not just think ‘faster’ or ‘more’ than younger ones; they also think in entirely different ways, employing cognitive abilities and structures that enable them to understand some problems and concepts completely beyond the grasp of younger children. In short, intelligence develops qualitatively with age, as well as quantitatively." (Fancher, 1996, p. 428-429).
Through a number of systematic observations of his daughter Jacqueline and her cousin Gerard, Swiss psychologist Jean Piaget began to develop a serious of developmental stages of intelligence. These stages were refined after Piaget secured a position with Theodore Simon to standardize the French translations of a series of reasoning tests. In testing a number of children, Piaget found he was much more interested in the students’ failures on the tests than the correct responses. He sought to explore the reasoning processes underlying the incorrect responses. Piaget concluded that intelligence is a developmental process, and children must pass through a number of stages before they reach "mature intelligence."

Piaget developed a program of genetic epistemology (meaning developmental, not heritable) to study the development of child intellect.

William Stern (1871-1938)  
German psychologist William Stern found a discrepancy in the method Binet proposed to calculate the intelligence scores on the Binet-Simon tests. Specifically, he noted that the discrepancy between chronological age and mental age often increased over time; therefore, the 2 year difference suggested by Binet was not sufficient as children aged. In 1912, Stern suggested the use of a ratio of mental age to chronological age to calculate a single intelligence score from the Binet-Simon tests. He referred to this ratio as the "intelligence quotient," a term which continues to be used today.
Lewis M. Terman (1877-1956)  
Stanford University psychologist Lewis Terman was the first to argue persuasively for the utility of the Binet-Simon tests in uncovering superior intelligence. Terman adapted the Binet-Simon scales for Americans in 1916. The revised scale has since been known as the Stanford-Binet Intelligence Tests, and continues to be in use today. Terman also modified the intelligence quotient concept proposed by Stern; he suggested that the fraction be multiplied by 100 to eliminate decimals. Since then, average intelligence has been denoted as an IQ of 100.

In contrast to Binet who diagnosed inferior children, Terman was interested in using intelligence measures to identify intellectually superior children. He tested more than 250,000 children to identify a group of "gifted" children with IQ’s above 140. While Terman hypothesized that these "gifted" children would develop into intellectually superior adults, the results of his longitudinal study did not support this hypothesis. However, the group overall fared above average in comparison to the national population in terms of higher education, income and health.

Charles Spearman (1863-1945)  
In examining correlations of various subtests of intelligence, Spearman noted that certain subtests tend to intercorrelate higher than others. To explain this, "Spearman theorized that all intellectual tasks must entail the exercise of a single common ‘factor’ he called ‘general intelligence’ (g)"… and that "each individual type of item required an ability specific to itself, an ‘s" factor" (Fancher, 1996, p 420). His theory, which became known as the two-factor theory of intelligence, likened the g factor to an individual’s overall supply of mental energy, and the s factor to a specific neurological "engine" for the performance of a particular task. Thus a person’s performance is the combined result of both the g factor and the specified s factor; however, the most important factor, according to Spearman, was general intelligence. In contrast to Binet, who believed that intelligence could not be adequately represented by a single number, Spearman suggested that g was the most important feature of individual intellect.
Louis Thurstone(1887-1955)
Thurstone was an American psychometrician who developed applied statistical procedures (factor analysis) to study psychological problems. Thurstone took Spearman’s theory further by identifying 7 factors that contributed to the g factor: (1) Verbal; (2) Word fluency; (3) Number facility; (4) Spatial; (5) Associative memory; (6) Perceptual speed; (7) reasoning.
Arthur Jensen  (1923 - ) 
An American educational psychologist who was a major proponent of the hereditarian position. He developed a two level theory of Intelligence: 
(1)Associative abilities (identifying and classifying shapes)

(2)Reasoning & Problems solving abilities

Howard Gardner(1943 - )
Gardner was an American psychologist and educator who wrote “Frames of Mind.” Based in part on the existence pf idiot savants and prodigies, Gardner argued that there are multiple types of intelligence and that traditional IQ tests do not measure all of these types. He proposed 8 factors of intelligence: (1) Linguistic; (2) Logical/mathematical; (3) Musical; (4) Spatial; (5)Bodily/kinesthetic; (6) Naturalist; (7) Interpersonal; and (8) Intrapersonal.
Robert J. Sternberg(1949 - )  
Sternberg is an American cognitive psychologist who developed the Triarchic theory of intelligences. Sternberg claims Successful Intelligence: should focus on the ability to adapt to shape, and select environments to accomplish one’s goals.Triarchic Theory’s three dimensions: 
·Creative Dimension (unique & novel solutions, ideas, artistic form, or products.) 

·Analytic dimensions (solving specific problems that have one correct and complex answers)

·Practical Intelligence (social competence, wisdom, and emotional intelligence)