Louis Leon Thurstone made significant contributions in many areas of psychology, including psychometrics, statistics, and the study of human intelligence. He developed methods for scaling psychological measures, assessing attitudes, and test theory, among many other influential contributions. He is best known for the development of new factor analytic techniques to determine the number and nature of latent constructs within a set of observed variables.
Thurstone considers intelligence as a mental trait and the capacity to make impulses focal at their early, unfinished stage of formation. To him therefore, Intelligence is the capacity for abstraction, which is an inhibitory process. Zeichner (2007) defines intelligence as the ability to learn quickly, solve problems, understand complex and abstract issues and generally behave in a reasonable, rational and purposeful manner.
Intelligence derives from the Latin verb intelligere, which means to comprehend or perceive. It is the mental quality that consists of the abilities to learn from experience, adapt to new situation, understand and handle abstract concepts and use knowledge to manipulate ones environment.
Intelligence can also be described as being able to think logically, analyze issues, and solve problems and to cope with life in a new environment. Thurstone (1887-1955) offered a differing theory of intelligence. Instead of viewing intelligence as a single, general ability, Thurstone's theory focused on seven different "primary mental abilities. (Schmuck, 2006).
Under this theory there generally seven key terms that are discussed and they are known as the primary mental abilities. These are Verbal comprehension, word fluency, number facility, spatial visualization, inductive reasoning, memory and perceptual speed.
Verbal comprehension involves the knowledge of vocabulary and reading. This test consists of a picture vocabulary for young children and the verbal vocabulary for elder ones. The purpose is to determine how well the learner understands what is said. (Schmuck, 2006).
Word fluency involves writing and producing words. Number facility involves solving fairly simple numerical computation and arithmetical reasoning. This tests how quickly and accurately one works with numbers. Spatial visualization involves visualizing and manipulating objects. This is used to test whether one is able to visualize objects and figures as they rotate in space. (Hayes, 2006).
Inductive reasoning involves completing a number of series or predicting the future on the basis of past experience. It also test how well one can find a solution to a logical problem. Memory involves recalling or knowing people names or faces.
Perpetual speed involves rapid proof leading to discover typographical errors in a text. Perpetual speed also examines how quickly and accurate one is able to detect the differences and similarities between a number of given objects or symbols. (Hayes, 2006).
Thurstone identified the above abilities after creating a set of 56 tests. His wife Thelma helped him to create this test set. Then they administered this test set to 240 college students and from the results analysis, Thurstone, developed the Primary Mental Abilities theory.
The new statistical techniques developed by Thurstone provided the necessary tools for his most enduring contribution to psychology: The Theory of Primary Mental Abilities, a model of human intelligence that challenged Charles Spearman’s then-dominant paradigm of a unitary conception of intelligence.
Zeichner, K. (2007) reveals that Spearman, using an earlier approach to factor analysis, found that scores on all mental tests (regardless of the domain or how it was tested) tend to load on one major factor. Spearman suggested that these disparate scores are fueled by a common metaphorical “pool” of mental energy. He named this pool the general factor, or g factor (mental quality that consists of the abilities to learn from experience, adapt to new situations, understand and handle abstract concepts, and use knowledge to manipulate one's environment.
Much of the excitement among investigators in the field of intelligence derives from their attempts to determine exactly what intelligence is. Different investigators have emphasized different aspects of intelligence in their definitions. For example, in a 1921 symposium the American psychologists Lewis M. Terman and Edward L. Thorndike differed over the definition of intelligence, Terman stressing the ability to think abstractly and Thorndike emphasizing learning and the ability to give good responses to questions.
Russell, T. & Loughran, J. (2005) argued that Louis Leon Thurstone made significant contributions in many areas of psychology; this includes psychometrics, statistics, and the study of human intelligence. He came up with methods for scaling psychological measures, assessing attitudes, and test theory, among many other influential contributions. He is best known for the development of new factor analytic techniques to determine the level of intelligence using the seven primary mental abilities.
According to Hayes (2006), Thurstone argued that g was a statistical artifact resulting from the mathematical procedures used to study it. Using his new approach to factor analysis, Thurstone found that intelligent behavior does not arise from a general factor, but rather emerges from seven independent factors that he called primary abilities.
Furthermore, when Thurstone analyzed mental test data from samples comprised of people with similar overall IQ scores, he found that they had different profiles of primary mental abilities, further supporting his model and suggesting that his work had more clinical utility than Spearman’s unitary theory. However, when Thurstone administered his tests to an intellectually heterogeneous group of children, he failed to find that the seven primary abilities were entirely separate; rather he found evidence of g. Thurstone managed an elegant mathematical solution that resolved these apparently contradictory results, and the final version of his theory was a compromise that accounted for the presence of both a general factor and the seven specific abilities. This compromise helped lay the groundwork for future researchers who proposed hierarchical theories and theories of multiple intelligences.
Thurstone was especially concerned with the measurement of people’s attitudes and intelligence. He attacked the concept of an ideal mental age, then commonly used in intelligence testing, advocating instead the use of percentile rankings to compare performance. He also developed a rating scale for locating individual attitudes and opinions along a continuum between extremes (Ackerman, R. & Mackenzie, 2007).
Having developed procedures for factor analysis, Thurstone carried out a number of factor-analytic studies, often in collaboration with his wife Thelma. In 1938 he reported his first findings on aptitude factors, which he called "primary mental abilities." This study involved a battery of 57 tests administered to 240 superior university students. Zeichner, K. (2007). States that similar studies were made with children in different age groups, even at the kindergarten level, showing essentially the same primary mental abilities at all levels. He subsequently developed and published for general use two different test batteries (for two age groups) for measuring five of the primary mental abilities. These are commonly known as the Thurstone PMA batteries.
In the light of Thurstone's Primary Mental Ability Theory of Intelligence following steps should be taken in Education -Giving the Intelligence Tests - In order to see the strength of different primary mental abilities in the students, teacher should administer the standardized intelligence test on the students.
According to Thurstone the teachers are encouraged not to judge the intelligence of their pupils on one basis instead should take time to see how well one can do or perform in other aspects of education. This is so because the pupil can be doing well in other things while not performing well in another and this does not mean the child is dull. (Samaras, A. & Freese, A, 2006).
In some cases it has been noted that some students do well in verbal comprehension but not doing well when it comes number facilities. It is now the duty of teachers to help these pupils who do not do well in other mental abilities, the teacher can do so by giving the exercises that are to develop these lacking areas in pupils.
Classification of the Students - The students should be classified in different Categories or sections on the basis of their primary mental abilities. This is to help the teacher can attend to a particular group with a particular task meant to help them appropriately. (Barone, T. & Eisner, E, 2006).
Samaras, A. & Freese, A (2006) suggest for a diversified Curriculum - In order to help the students to opt for the subject sand activities according to their primary mental abilities a diversified curriculum should be introduced in the educational institution.
Co-curricular activities - In order to develop the different primary mental abilities among the students various types of co-curricular activities should be organized in the educational institutions (Barone, T. & Eisner, E, 2006).
Providing Freedom - In order to give full expressions to the innate potentialities, talents and abilities maximum freedom should be given to the students.
Schmuck, R. (2006) states that there should be the Introduction of creative activities -Some creative activities like art and craft, drawing, painting, music, singing, dancing, dramatics, clay modeling and such other activities should be introduced in the curriculum for developing different primary mental abilities of the students. Admission to various courses: Admission to various courses should be given on the basis of the strength of the primary mental ability of the students.
In conclusion, having looked at Thurstone theory of intelligence, the essay has highlighted the main terminologies of this theory and how this theory can be used by educators to ensure effective learning and teaching in the education setting. It is therefore important that teachers should strive to apply all the seven primary mental abilities highlighted in Thurstone’s theory of intelligence

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