Carroll's theory of the Three Strata of Intelligence

The theory of the three layers of intelligence by John B. Carroll proposes that the factor structure of human cognitive abilities is composed of a general intellectual capacity (the g factor), a set of 8 abilities broad, such as mental processing speed or memory, and a third layer that would include more specific intellectual abilities and dependent on one of the previous.

In this article we will analyze the Carroll model, which today is usually studied and applied together with the theory of fluid and crystallized intelligence proposed by Cattell and Horn. We will focus in particular on the analysis of each of the intelligence strata that were described by this author.

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John Carroll's theory of intelligence

The American psychologist John Bissell Carroll (1916-2003) is known mainly for his contributions in the field of psychometrics around the measurement of phenomena such as intelligence, language skills or performance academic. On the other hand, his theoretical approaches to cognition and language are also very relevant.

In particular he highlights his theory of the three layers, a model based on the results of hundreds of factor analyzes on samples of numerical data that can serve as predictive variables of intelligence, such as IQ tests or grades obtained on assessment tests academic.

Carroll presented the results of his studies along with his theory of intelligence in a work entitled “Human Cognitive Abilities: An Investigation of Factor-Analytic Studies,” which was published in 1993. In this book he emphasized the distinction between aptitudes related to individual differences and those derived from the quality of education.

At present the theory of the three layers of Carroll It is considered complementary to the Raymond B model. Cattell, and John L. horn (focused on the division between fluid and crystallized intelligence), which Carroll himself had defended before creating his own. The assimilation of both perspectives into one can be attributed to Kevin McGrew (2012).

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The three layers of cognitive aptitude

Carroll's theoretical proposal can be included in the category of hierarchical models of intelligence, since he describes three layers that go from the most specific samples of cognitive aptitude to its general aspect, which is specified in the construct “g-factor”. These aptitudes would have a stable character, according to the author.

Carroll claimed that these abilities can probably be attributed to physiological variables. In this sense, it is worth mentioning that authors such as Philip Vernon (who developed his own theory on the structure of intelligence) and Hans Eysenck have related cognitive skills to the efficiency and quality of transmission neural.

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1. First layer: primary mental abilities

According to Carroll, the lower layer of the structure of intelligence is made up of primary mental abilities, which include a large number of cognitive abilities: quantitative reasoning, spelling, visualization, aptitude for foreign languages, discrimination of speech sounds, fluency of ideas, reaction time, etc.

The results of the factor analyzes carried out by Carroll and other subsequent authors reveal that each of these aptitudes, which have a high degree of specificity, are weighted in one of the complex factors of the second stratum depending on the characteristics of the stimulated material and the overall ability on which they depend.

2. Second layer: complex factors

At this level we find a set of broad cognitive skills. Originally Carroll proposed the presence of 10 factors in the second stratum, although later research reduced the number to 8:

• Fluid intelligence: the ability to reason and solve problems using new information.
• Crystallized intelligence: refers to the depth and amount of verbal knowledge acquired and the handling of this type of data.
• General memory and learning: the ability to learn in general along with specific abilities such as retaining information or retrieving it in the short term.
• Broad resiliency: includes the skills to fluently handle ideas and associations, both verbally and visually.
• Visual processing: capacity that allows to perceive, analyze, remember and operate with visual stimulation.
• Auditory processing: ability to discriminate and process sounds, including those associated with speech and music.
• Broad cognitive speed: refers to the speed to handle stimuli during tests (eg. and. the numbers) and to complete them.
• Processing speed: ability to execute automatic cognitive processes, particularly by maintaining selective attention.

Each of these factors encompasses various lower order factors corresponding to the first stratum. Thus, for example, crystallized intelligence includes reading comprehension, spelling, and aptitude for foreign languages, while the broad recovery capacity is derived from tests of creativity and fluency with different types of material.

3. Third stratum: general intelligence or g factor

The third layer of the structure defined by Carroll is made up of the general intelligence factor, a construct known as the “g factor” and used by a large number of psychologists. This higher order aptitude would influence all the aptitudes included in the second stratum, and therefore also those of the third in an indirect way.

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