Raymond B. Cattell’s theory of intelligence is one of the most influential in this field of study.

This multifactorial and hierarchical theory proposes that there is a general intelligence factor that depends on genes and is manifested in multiple cognitive abilities, which factor analysis groups into two factors: fluid and crystallised intelligence .

Cattell’s theory of intelligence

Raymond Bernard Cattell (1905-1998) was an English psychologist who became famous for his psychometric research on the human mind , which focused particularly on personality and intelligence. From factorial analysis, in which he was a pioneer, he developed two very influential theories on these psychological constructs.

Other topics that interested Cattell included motivation, emotion, learning, creativity, academic and professional orientation, and social interaction. However, he is best known for his factorial theory of personality and for the 16PF questionnaire, which was derived from his model and remains one of the most widely used today.

In this author’s work, the influence of the statistician Charles Spearman is very notable, who used factorial analysis even before Cattell. In particular, Cattell’s theory of intelligence is derived from Spearman’s bifactorial theory, which argued that there is a general cognitive factor (g) that explains lower level abilities.

John L. Horn, a disciple of Cattell, later developed his theory, focusing on fluid and crystallized intelligence; so did John B. Carroll. This is why the theory we will describe in this article is often called “Cattell-Horn-Carroll theory” .

First-order cognitive skills

Through factor analysis Cattell identified a series of primary factors that structure intelligence . He paid special attention to the first two, which he identified with fluid and crystallised intelligence; we will discuss these two factors in detail in the following section.

1. Fluid reasoning

This skill consists of the flexible and deliberate use of mental operations to adapt to new situations and to solve problems in which one has no experience. It is also known as fluid intelligence and includes processes such as inductive and deductive reasoning, concept formation, classification and identification of relationships.

2. Understanding-Knowledge

The Understanding-Knowledge factor, which corresponds to crystallized intelligence, is the knowledge accumulated during life and is influenced by the socio-cultural context as well as the educational level. It is fundamentally based on learning verbal and procedural information .

3. Quantitative knowledge

Quantitative knowledge is defined as the amount and depth of numerical and mathematical knowledge, both at a declarative and procedural level. It is acquired mainly through formal education, and is therefore associated with crystallized intelligence.

4. Reading and writing skills

This factor is similar to the previous one, although in this case the material is not mathematical but linguistic. Skills such as reading comprehension, spelling ability, knowledge of languages and reading speed are related to this aptitude.

5. Short term memory

For Cattell, short-term memory is the capacity to retain and handle information obtained at the last minute, approximately; therefore, in current terms it would be more appropriate to think of operating memory when conceptualizing this factor.

6. Long-term storage and retrieval

This skill is associated with long-term memory and also with operational memory , since it encompasses the sub-factors that allow the consolidation of information in the memory, as well as its recovery and management. Among the related factors we find free memory, fluidity in the association of ideas, ease of denomination and creativity.

7. Visual processing

Cattell defined visual processing as the ability to generate, store, retrieve and modify images . This factor includes others of a lower order such as visual memory, visualization, visual pattern detection, spatial scanning and mental rotation.

8. Auditory processing

The tasks involving sound perception and the functioning of the auditory system are related to this aptitude. Sub-factors that make up auditory processing include frequency and tone discrimination, resistance to sound distortion and memory for sound patterns.

9. Processing speed

This factor is defined as the ability to carry out easy or overlearned cognitive tasks efficiently. It is associated with different types of material; for example, both the speed of calculation and the speed of reading and writing depend on this aptitude, but so do the speed of reasoning and the speed of perception.

10. Reaction and decision time

The tenth major skill described by Cattell is the ability to respond or make decisions quickly to the appearance of particular stimuli. It weighs the time of choice between alternatives, the speed of semantic processing and mental comparison, among other inferior factors.

Fluid and crystallized intelligence

Cattell gave great importance to two of the primary cognitive skills : Comprehension-Knowledge and Fluid Reasoning . He considered that these two factors, which he called “crystallised intelligence” and “fluid” respectively, explained the rest to a large extent. This dichotomy is still very popular in the psychology of intelligence.

According to this author and many subsequent studies, fluid intelligence has an important genetic-hereditary component , it is influenced by physical condition, decreases in old age and is involved in solving new problems. This type of intelligence includes aptitudes such as spatial reasoning, memory and speed of processing.

In contrast, crystallized intelligence is derived from learning ; consequently, it is more influenced by culture and socialization than fluidity, and is not as affected by age. Verbal skills depend mainly on crystallized intelligence, and executive functions are also influenced by it.

Cattell’s analyses also identified a general factor underlying both fluid and crystallised intelligence: historical fluid intelligence, which is basically equivalent to the “g” factor described by Spearman and many later authors. This cognitive nuclear factor has a biological character and is related above all to fluid intelligence.

Therefore, and despite the fact that Cattell’s theory of intelligence is usually classified as a multifactorial model, it is also true that it has a relevant hierarchical component. Fluid intelligence influences different aptitudes, many of which also weigh on a primary factor related to learning (crystallised intelligence).