Human Cognitive Abilities — Ch. 2 (Carroll)

Carroll, J. (1993). Human Cognitive Abilities [Chapter 2]. New York: Cambridge. “Historical Foundations of the Study of Cognitive Abilities”

This chapter begins with a brief historical account of the field of mental testing, followed by a discussion of defining intelligence. Carroll also provides a summary of the development of the factor analysis method to investigate cognitive abilities and includes the major models of intelligence.

The first known scientific inquiry into the individual differences in mental ability occurred in the early 19th century, when an astronomer named Bessel noted differing reaction times in subjects. Later, this subject of mental ability differences was taken up by the likes of the German psychologist Wundt [1832-1920], his American student James McKeen Cattell [1860-1944] (who coined the term “mental test”), and then most notably Francis Galton [1822-1911]. Even though Galton failed to measure intelligence through psychometric tests, he is credited for introducing notions such as correlation and percentile that proved to have a significant influence 0n the field, as well as introducing the use of important types of statistical distributions (e.g., Gaussian normal distribution). Karl Pearson, G.U. Yule, Spearman, and Burt all owe a debt to Galton’s work.

Later Binet [1857-1911] and Simon developed a scale of intelligence, based on tasks measuring understanding of language and the ability to reason verbally, spatially, numerically. The “Stanford-Binet” individual test of intelligence is the product of that work. Critics of Binet’s scale charge that measures a “melange of somewhat independent abilities” (p.32). Although Ebbinghaus [1850-1909] is credited with having devised the first group test of intelligence, most group tests (ex: Army Alpha Examination) were modeled after Binet’s set of tasks.

Developments in the field of statistics in the early 1900s also contributed to the advancement of this field. Pearson’s group developed the statistics of linear correlation and multiple regression, estimations of statistical parameters, and other concepts related to mental test construction and evaluation. Charles Spearman developed the concept of test reliability around this time; he is also the architect of  “classical test theory,” which states that “any test score is composed of two components, a ‘true score’ and an ‘error’ score representing the operation of random fluctuations” (p.34). Spearman authored a seminal paper in 1904 in which he explained the correlation between various mental ability tests in terms of a theory of individual differences in intelligence. In particular, he proposed a General Intelligence factor (g), that could account for each variable in his experiment. This lead to his “two-factor” theory of intelligence — that each variable may be accounted for by a general factor and a specific factor unique to that variable.

Another important and far-reaching influence was the development item response theory (see p. 34-35 for discussion).

Scientists working in this field also struggled with a satisfactory definition of intelligence. Writes Carroll (from the proceedings of a 1921 symposium):

Intelligence was variously described as “ability to learn” (Buckingham, p. 273), as “the power of good responses from the point of view of truth or fact” (Thorndike, p. 124), as “the ability to carry on abstract thinking” (Terman, p. 128), as “the ability of the individual to adapt himself adequately to relatively new situations in life” (Pinter, p. 139), as “involving two factors – the capacity for knowledge and the knowledge possessed” (Henmon, p. 195), and as “the capacity to acquire capacity” (Woodrow, p. 207) (p. 36)

A survey of more contemporary researchers (at a 1986 symposium) indicated a desire to understand behavior, as opposed to measuring or predicting it:

Anne Anastasi conceives of intelligence as a quality of adaptive behavior. J. W. Berry regards intelligence as the end-product of individual development in the cognitive- psychological domain. Carroll (the present writer) emphasizes that intelligence is a societal concept that operates in several domains – academic, technical. social, and practical. Hans Eysenck concentrates on intelligence from a biological point of view, arguing that it derives from the error-free transmission of information through the cortex. Howard Gardner describes the theory of multiple intelligences that he has expounded elsewhere (Gardner, 1983). Robert Glaser views intelligence as acquired proficiency. Arthur Jensen defines intclligence in terms of the general factor obtained in many studies of psychological tests. John Horn, however, thinks that intelligence is the reification of a functional unity that does not in fact exist: he prefers to think of intelligence in terms of a number of somewhat indcpendent broad abilities. Lloyd Humphreys describes intelligence as the repertoire of intellectual knowledges and skills available to a person at a particular point of time. Robert Sternberg defines intelligence as “mental self-government” (p.36).

Carroll also provides a comprehensive history of the development of the factor analysis method to investigate cognitive abilities.

Factorially-derived models of intelligence include: Spearman-Holzinger Model (p.52-4); Thurstone’s Model of Cognitive Abilities (p.54-7); Guilford’s Structure-of-Intellect Model (p.57-60); Vernon’s Hierarchical Model of Intelligence (p.60-1); Cattell and Horn Hierarchical Model of Cognitive Abilities (p.61-2).

“Spearman and his followers attached greatest importance to the general factor and only subsidiary importance to various group or primary factors. Thurstone attached less importance to Spearman’s general factor and in fact pointed out that there might be several factors at the second or higher orders; primary factors, he believed, were of considerable importance and utility in vocational guidance and other contexts” (p.56). (Carroll points out that if the general factor and group factor variances are calculated for each variable, it becomes clear that group factors may be nearly as important at the general factor in determining common factor variance on a test). Spearman was actually much more interested in probing the “laws” of cognition than measuring individual differences; he believed that g “embodied general laws of cognition better than any group factor might do” (p.68). Despite this interest, the field of cognitive psychology did not become a recognized subfield of psychology until the 1960s.

Aptitude-treatment interaction theory — “how aptitudes may interact with learning processes such that learners with different aptitude profiles may adopt different learning strategies, or require different types of instruction of optimal success in learning” (p.71). It has been observed that students will choose different strategies to complete different tasks, based on task difficulty and the student’s aptitude level.

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