What is intelligence? Models, approaches and schools

The intelligence Has been defined in several ways, including the ability to have logic, understanding, self-awareness, learning, emotional awareness, planning, creativity and problem solving.

Intelligence is studied more widely in humans, although it has also been observed in animals and plants.


The study of intelligence Has been an issue that has generated great interest and curiosity in society and has been increasing and perfecting throughout history.

From different approaches has tried to define as accurately and completely as possible the concept of intelligence, however, this task is not easy because there are many factors involved.

When we speak of intelligence we usually do so intuitively, however, behind this concept there are endless approaches (scientific, deterministic, genetic, environmental...), authors and opinions, who have tried to answer such questions as; What is intelligence?; How is it developed?; Is intelligence a structure? Is intelligence a process?

The study of intelligence has been closely linked to the birth of Differential psychology , Whose objective is the study of the individual differences existing between people as:

  • If people are more like themselves than others.
  • If the individual varies less than the variation that could be given between people.

This psychology addresses the description, prediction and explanation of interindividual (between individuals), intergroup (intragroup) and intraindividual variability (in the same individual), in relevant psychological areas with respect to their origin, manifestation and functioning.

History of intelligence

The investigation into what intelligence was and the first definitions put forth begin in antiquity.

At Classic world Plato Understood the intelligence based on the"capacity to learn", that is, the level of ease or difficulty for the acquisition of knowledge and memory or conservation of them.

Plato proposed that there were no two equal individuals from birth, and that these according to their specific talent had to adapt to a particular occupation, dividing the citizens into:

  • Guardians: those with a rational soul.
  • Assistants: those with an irascible soul.
  • The rest: those with an appetite.

On the other hand, Aristotle Said that intelligence was understood as an entity distinguishable from other human qualities.

In the Middle Ages , There is a decrease in interest in individual differences, except for the religious and moral mood. So, San Agustin Defined individual intelligence as the speed of comprehension and the precision and sharpness of discernment.

Between the S 17th and 19th century , There is a scientific revolution in which reason predominates. Kant Spoke of intelligence as the superior faculties of cognition based on understanding, judgment and reason.

Intelligence from different schools

A new development is thanks to Galton , Founding father of differential psychology, who proposes the creation of tests and evaluation strategies with the objective of obtaining direct measures of the mental functions and also creates the first mental tests. Galton was the first to propose that there was only one intellectual capacity.

For its part, since the American School, JM Cattell , Proposes the mental tests to measure simple and specific processes whose answers reflect the intellectual capacity of the people.

In the English School highlights Spearman , Who was interested in the correlations that maintain the mental tests among themselves, proposing the existence of a single intellectual capacity, as Galton did. Spearman proposed the Bifactorial Theory of Intelligence.

In the French School we find Alfred Binet , A relevant author in the study of intelligence that took a turn with respect to what was studied by Galton and Cattell (see comparative table).


He focused on the study of higher and complex mental processes as vivid imagination, attention, verbal ability, ability to discover errors with a text...

In addition, he proposed an environmentalist conception of intelligence, that is, people's abilities could be modified and proposed mental orthopedics (compensatory education), whose objective was to increase the intellectual level of the mentally retarded.

Together with Simon, he created the Metric Intelligence Scale To measure intelligence in school children. This was composed of sensory, perceptual and high verbal content tests.

In it, the mental age score was obtained, that is, the chronological age of subjects who had on average the same score as that subject. The objective was to define mental retardation and did it through the difference between mental and chronological age.

Other authors that stand out in the Psicotécnica (interrelation between the Differential Psychology And applied), were Stern, Terman Y Weschsler .

In 1911 Stern, he defined the Mental quotient As the quotient between mental age and chronological age (subject's age).

In 1916 Terman defined the I.Q , Which is the index that is usually used to classify subjects intellectually and consist of the quotient, multiplied by 100, between the mental age and chronological age of a subject.

And Wechsler, for his part, talks about the c IQ , Which is the starting point for estimating CI. It is the dispersion of the yield around the average value of the age group to which it belongs.

After these first approaches to the study and evaluation of intelligence, there were two approaches to the study of intelligence. On the one hand the structural-factorial approach, interested in the determination of the main properties or dimensions.

And on the other, the interest in the processes, with the incorporation of knowledge of cognitive psychology and variables such as emotion and motivation. In addition, the application of information processing models to the field of individual differences is given. Cognitive processes begin to be studied with psychometric measures. For example:

  • Approach to cognitive correlates : Studied by relatively simple experimental tasks.
  • Approach to cognitive components : Studied with complex cognitive tasks.
  • Psychophysiological correlates : Based on the study of simple processes.

Approaches to individual differences in intelligence

Interest in the study of the structure of intelligence arises from a general concept of intelligence, such as implicit intelligence.

Implicit or legal intelligence is one that guides the way people perceive and evaluate intelligence. In this way, they help us to understand differences in the development of intelligence and cultural differences.

For example, several studies in the US, Taiwan, or Zambia have found several differences. In the United States greater importance is given to intelligence such as the ability to solve practical problems, verbal ability and social competence. While in Taiwan or Zambia, intelligence is based on interpersonal skills, cooperation, social responsibility and cognitive abilities.

Major trends in the study of individual differences

In the study of intelligence different metaphors are proposed, each involved in a different goal. We find the geographical or structural, the computational, the biological, the systemic and the anthropological.


Intelligence A, B, C

In relation to the models seen above Hebb reformulates it and proposes that there are two types of intelligence: A and B.

Intelligence A is the biological, genetically determined and mediated by the complexity and plasticity of the CNS. It implies an innate potential to be able to learn and adapt to the environment. Intelligence B is social or practical and supposes the manifestation of intelligence in the everyday environment of individuals.

Shortly after Vernon, adds a third, C. Intelligence C is the psychometric, and is the one that measures the test.

Structural models of intelligence

The structural models of intelligence are aimed at describing the intelligence and elaboration of cognitive performance taxonomies based on individual differences.

They are classified in:

Non-Hierarchical Factorial Models

They point to the existence of independent capacities that are not related or part of a superior structure.

Within the non-hierarchical models we find the following:

  • Thurstone's Primary Capacity Model . It evaluates 7 independent factors: inductive reasoning (ability to elaborate, verify hypotheses and discover general rules); Memory (ability to remember and recognize information); Numerical capacity (fast and accurate calculation); Perceptual speed (detection and recognition of stimuli); Spatial visualization (recognition and manipulation of forms in space); Verbal comprehension (verbal content comprehension) and verbal fluency (verbal fluency expression).
  • Cubic Model of Guilford Intellect Structure . It evaluates between 120 and 150 independent skills or abilities that derive from the combination of the contained dimensions, operations and products.

Pure hierarchical factorial models

They assume that capacities in intelligence are ordered from less relevance to a higher level of abstraction. They start from basic skills and abilities that will be grouped together until the general factor or factor G, defined by Spearman.

Within the hierarchical factorial models exist:

  • Spearman's Bifactorial Two-Factor Theory . There was a general factor that represented the mental energy characteristic of the subject present in all tests of mental capacity and an indeterminate number of specific factors"s"characteristic of the different tasks or tests, which in turn depended on general intelligence.
  • Hierarchical model of mental levels of Burt . This author stated that there were five hierarchical levels in intelligence: general intelligence (higher level); the relationship; the Asociation; Perception and sensation (most basic level).
  • Hierarchical Vernon Intelligence Model . This author established the existence of four levels of generality: general intelligence factor; Major group factors (verbal-educational and spatial-mechanical factor) and specific factors.
  • Cattell-Horn model (hierarchical integrator) . Where three levels of different generality are established: third order factors (where we find historical intelligence and learning); Second order factors (where we find fluid and crystallized intelligence, visual intelligence, resilience and cognitive speed) and first order factors (primary aptitudes).

Mixed Hierarchical Factorial Models

They attach importance to hierarchy, but in turn, focus on middle-level units.

Within the mixed hierarchical models we find:

  • Hierarchical Factorial Model HILI by Gustafsson , Which proposes the existence of a G factor, and five factors located at an intermediate level (fluid, crystallized, visual intelligence, resilience and cognitive speed) and on the basis of primary factors.
  • Model of the three strata of Carroll , Which proposes that within the third extract we find the factor G; Within the second, 8 such factors as (fluid and crystallized intelligence, memory and learning, visual and auditory perception, resilience and cognitive speed) and, lastly, Guilford's similar skills.

Processional intelligence models

These models are based on the fact that intelligence involves the interaction of different cognitive, biological and contextual systems, which implies not a single concept, but a wide range of skills. It is a dynamic thing that can change when there are changes in the functions of the environment.

With respect to intelligence and cognitive processes, numerous studies have been carried out through simple tasks of mental velocity, reaction time, inspection time... and the results are as follows.

Smarter people invest less time in issuing a response (reaction time) and less time in recognizing the stimulus they have ahead (inspection time). That is, they are faster and more consistent. In addition, people with a higher IQ have less intra-individual variability.

Approach to cognitive correlates

He Approach to cognitive correlates Is centered in the operations that take place in the accomplishment of a task, and they argue that the differences in intelligence of the individuals are due to the existing variations in the speed of execution of these basic processes. However, the studies state that it can not be concluded that psychometric differences in intelligence are caused by the basic cognitive processes involved in performing the tasks used.

This approach fails, since it was deduced that individual differences in intelligence were more related to effectiveness than to speed.

Approach to cognitive components

As a result, the Approach to cognitive components Which uses complex cognitive tasks, and here we find a model and two different theories.

He Rational model of Carroll Breaks down the characteristics of the cognitive tasks of a test battery, that of French. He finds that the variety of factors of individual differences seems to be produced by the interaction of a reduced number of elementary processes with different kinds of stimuli and forms of response, sensory modalities, and memory stores.

The Sternberg's componential theory , Is a theory that speaks of the model of cognitive component of intelligence. In it he postulates that there are three hierarchical components:

  • The metacomponents, which are the executive processes of higher order control, are responsible for deciding the problem to be solved and how to carry it out.
  • The execution components, which are usually specific to the problem to be solved and involved in the development of strategies.
  • Knowledge acquisition components: involved in learning and storing new information.

Regarding the relationship between intelligence and biological processes, the following results are observed in relation to nerve conduction velocity, evoked potentials and energy consumption.

In speed it is observed that to greater intelligence, greater mental speed and neural speed. In evoked potentials, a higher intellectual quotient, lower latency of response, less variability of evoked potentials, and greater breadth of potentials evoked by new and unexpected stimuli are observed. With respect to energy consumption it is observed that the most intelligent people consume less glucose.

Finally, it was seen that the cognitive processes like thoughts, feelings and sensations are the result of variations in the neural activity of the networks.


Intelligence has been the beginning of many investigations and theories, and little by little we can get a better idea of ​​what it is to be intelligent and what it supposes, but there is still a way to go.


  1. Sánchez-Elvira, M.A. (2005). Introduction to the study of individual differences. Madrid: Sanz and Torres.
  2. Pueyo, A. (1997). Manual of Differential Psychology. Barcelona: McGraw-Hill.
  3. Pueyo, A. and Colom, R. (1998). Science and politics of intelligence in modern society. Madrid: New Library.

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