Thurstone’s theory of the 7 primary mental skills, Which appeared in the 1920s, is one of the most important psychological models of intelligence in existence.
The peculiarity of this author compared to others of the time was his focus on the manifoldness of intellectual abilities, thus opposing Spearman’s g-factor.
Thurstone’s theory of intelligence
Louis Leon Thurstone (1887-1955) is considered one of the most influential authors in the field of psychometry. His main contribution is his theory of the 7 primary mental skills., Which is opposed to the models of unitary and hierarchical intelligence proposed by other pioneers like Charles Spearman or PE Vernon.
In a very particular way, Thurstone denied the existence of a general intelligence factor (the famous “g-factor”) to which the rest of cognitive abilities would be subordinate. For this author intelligence was to be understood as a set of primary mental skills not reducible to a single higher level dimension.
Along with authors such as Charles Spearman and Raymond B. Cattell, Thurstone is considered one of the foremost leaders of the implementation of factorial analysis methods in psychology. These mathematical tests aim to identify the number and structure of the various factors that weigh in some sort of psychological measure.
Thurstone’s goal was to find an intelligence configuration faithful to empirical data but as simple as possible; in other words that is to say, he tried to explain the different skills that make up intelligence with a few higher order factors. Each of them maintained a strong correlation with a specific type of intellectual evidence.
The influence of Thurstone’s work has been very noticeable in later developments in the psychology of intelligence. Thus, we can draw inspiration from the model of primary mental aptitudes in the most recent versions of tests as important as the Wechsler intelligence scales and the Stanford-Binet intelligence scale.
The 7 main mental skills
After his first investigation, for which he used 56 different intelligence tests, Thurstone identified nine primary mental factors or abilities.
Many subsequent studies have repeatedly validated 7 of these factors, so we can say that Thurstone’s model has solid measurement capability.
1. Verbal comprehension (factor v)
The verbal comprehension factor is associated with knowledge related to the language in all its manifestations; it would therefore include vocabulary, semantics, syntax or pragmatics. Factor-weighted tests include tests of reading comprehension, ranking of text segments, spelling, verbal analogies, and more.
2. Verbal fluency (w)
This ability can be defined as the ability of a person to quickly and naturally emit coherent and structured verbal sequences. Several are used to measure it types of tests involving rapid speech production; thus, for example, the classic test of giving animal names starting with a given letter could be used.
3. Numerical aptitude (n)
Numerical aptitude tests mainly consist of basic mathematical calculations: addition, subtraction, multiplication and division. Although they can be more complex, simple arithmetic calculus tasks rely mainly on the factor n; the most relevant aspects are the speed of operations and the precision of responses.
4. Spatial aptitude (s)
The s factor manifests itself in spatial orientation, in the representation of objects in space or in rotational tasks; since these are very large capacities, spatial ability is divided into two or three secondary factors. Relevant tests involve predicting movements, comparing numbers from different perspectives, etc.
5. Associative report (m)
This factor is associated with a specific aspect of memory: the ability to keep associations of pairs of elements. In this way, tests involving pictures, words (in visual or auditory format), symbols, etc. are used to measure associative memory; they can be presented in the same modality or in combinations of more than one of these materials.
6. Perception speed (p)
All those weighing in the p factor cognitive tests based on the comparison between different items or in the identification of structures and sequences. Thus, the skill Thurstone called “speed of perception” refers to how quickly we find similarities and differences between various items.
7. General reasoning (r) or induction (i)
Some of the research that has been done around Thurstone’s model partly distinguishes the r factor from the i factor. While the second corresponds to the inductive thinking capacity (Search for general rules with predictive value from series of elements), “general reasoning” has a more marked mathematical weight.