Thurstone criticized the idea of unitary intelligence and proposed that it was divided into abilities.
Thurstone’s theory of the 7 primary mental abilities, which appeared in the 1920s, is one of the most important psychological models of intelligence in existence.
The differential characteristic of this author in relation to others of the time was his focus on the multiple nature 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 aptitudes, which opposed the unitary and hierarchical models of intelligence proposed by other pioneers such as 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 capacities would be subordinated. For this author, intelligence should be understood as a set of primary mental abilities that can not be reduced to a single higher-level dimension.
Along with authors such as Charles Spearman and Raymond B. Cattell, Thurstone is considered one of the main responsible for the establishment of factor analysis methods in psychology. These mathematical tests have the objective of identifying the number and structure of the different factors that weigh in some type of psychological measure.
Thurstone’s goal was to find a configuration of intelligence that was true to the empirical data but kept as simple as possible; that is, he tried to explain the different skills that make up intelligence with a few higher-order factors. Each of them had a strong correlation with a particular 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 find the inspiration for the model of primary mental aptitudes in the most recent versions of such important tests as the Wechsler Intelligence Scales and the Stanford-Binet Intelligence Scale.
The 7 Primary Mental Skills
After his first investigation, for which he used 56 different intelligence tests, Thurstone identified 9 factors or primary mental abilities.
Numerous subsequent studies have repeatedly validated 7 of these factors, so that we can say that the Thurstone model has strong measurement capabilities.
1. Verbal comprehension (factor v)
The verbal comprehension factor is associated with knowledge related to language in all its manifestations; it would therefore include vocabulary, semantics, syntax or pragmatics. The tests that weigh in factor v include tests of reading comprehension, ordering of text segments, spelling, verbal analogies, etc.
2. Verbal fluency (w)
This ability can be defined as the ability of a person to deliver coherent and structured verbal sequences quickly and naturally. To measure it, various types of tests are used that involve the rapid production of speech ; thus, for example, the classic test of giving animal names that begin with a certain letter could be used.
3. Numerical ability (n)
Numerical aptitude tests consist primarily of basic mathematical calculations: addition, subtraction, multiplication, and division. Although they can be more complex, the factor n is mostly weighted for simple arithmetic tasks; the most important aspects are the speed of the operations and the precision of the answers.
4. Spatial aptitude (s)
The s factor is manifested in spatial orientation, in the representation of objects in space or in rotation tasks; Since these are very broad capabilities, spatial aptitude is often divided into two or three secondary factors. The relevant tests involve the prediction of movements, the comparison of figures from different perspectives, etc.
5. Associative memory (m)
This factor is associated with a specific aspect of memory: the ability to retain associations of pairs of elements. Thus, to measure associative memory, tests involving images, words (in visual or auditory format), symbols, etc are used; They can be presented in the same modality or in combinations of more than one of these materials.
6. Perception speed (p)
In the p factor all those cognitive tests that are based on the comparison between different elements or on the identification of structures and sequences are weighted . Therefore, the aptitude that Thurstone called “speed of perception” refers to how quickly we find the similarities and differences between various items.
7. General reasoning (r) or induction (i)
Some of the research that has been carried out on the Thurstone model distinguishes in part the factor r from factor i. While the second corresponds to the capacity for inductive thinking (finding general rules with predictive value from series of elements), “general reasoning” has a more marked mathematical weight.