Understanding Spearman’s Theory of Intelligence 

Understanding Spearman’s Theory of Intelligence 


Have you ever wondered what your report card says about your intellectual abilities? Imagine you received good marks in all the subjects, but somewhat struggled in mathematics. This might impact your overall result, but what does this say about your overall intelligence? Well, Charles Spearman might have just the right answer for you. 

The Story of Spearman 

The English psychologist Charles Edward Spearman (September 10, 1863 – September 7, 1945) is well-known for his contributions to statistics and psychology. For a psychologist, Spearman’s background was peculiar. Spearman left the British Army after serving as an officer for 15 years to pursue a PhD in experimental psychology. Since psychology was mostly regarded as a subfield of philosophy in Britain, Spearman decided to study under Wilhelm Wundt in Leipzig. 

Francis Galton’s work had a big impact on Spearman. Galton created correlation, the primary statistical technique employed by Spearman, and conducted groundbreaking research in psychology. Based on his statistical work in identifying connections across mental talents, as evidenced in his landmark publication, “‘General Intelligence,’ Objectively Determined and Measured” (1904) Spearman attempted to create general, fundamental laws of psychology.

Even though Spearman’s statistical work garnered the most attention, he saw this work as secondary to his search for the underlying principles of psychology. 

Read More: Triarchic theory of intelligence

How do we define Intelligence? 

Intelligence is the ability to derive information, learn from experience, adapt to the environment, understand, and correctly utilize thought and reason (APA). One of the most discussed topics in psychology is intelligence, yet there is no single accepted definition of the term. According to certain scholars, intelligence is a single, all-encompassing skill. Some perspectives suggest that intelligence is made up of a variety of aptitudes, abilities, and talents. Though opinions on what defines intelligence in modern times are somewhat diverse, most experts believe that intelligence is the capacity for mental processes like reasoning, planning, logic, and problem-solving.

Spearman’s Theory of Intelligence

As the interest and curiosity around intelligence grew, so did the differences of opinions, with various beliefs and theories. One of these theories is Spearman’s theory of intelligence. 

The Two-factor Theory 

In 1904, Charles Spearman introduced his two-factor theory of intelligence. To develop this idea, he examined the various mental aptitude and cognitive tests that the participants took. 

After analyzing cognitive test results, the researcher noticed that individuals consistently performed similarly across different types of exams. This led him to conclude that there’s a strong link between overall intellectual capability and how people perform on various mental tasks.

To delve deeper, he used a statistical tool called factor analysis. This helped him identify underlying patterns in the test scores. What he found was that these scores weren’t random—they clustered together in a way that suggested a common factor influencing performance across different types of cognitive tests.

This common factor, referred to as the “g” factor or general intelligence factor, became a key part of his theory. Essentially, “g” represents a measurable quality that explains why some people perform well across a range of mental abilities. It suggests that our cognitive skills—like problem-solving, reasoning, and memory—are connected rather than independent.

In conclusion, the researcher’s work showed that intelligence-related traits can be measured and understood through the concept of “g.” This idea has had a big impact on psychology, shaping how we think about human intelligence and how it influences our abilities in various intellectual tasks.

From Spearman’s Point of view, you can imagine intelligence as a dish with two major ingredients. These are – 

1. g factor 

2. s factor 

Let us understand them in detail. 

The General factor 

The g factor for general intelligence refers to the capacity for reasoning and problem-solving. G factor would most likely be measured by a regular IQ test. Spearman discussed the biological underpinnings of general intelligence (g) and suggested that there was a broad general intelligence (g) factor at work. Spearman observed that there is a tendency for a variety of cognitive tasks and intellectual measurements to be associated with one another, meaning that those who perform well on one would likely perform well on the others. 

The Specific factor 

The s factor takes into account differences in certain skills. Task-specific skills in particular domains, like music, business, or the arts, are called specific intelligence factors. They refer to specific skills related to memory, vocabulary, numeracy, and spatial imagery, among other things. In addition to training, practice, and other contextual influences, g factor also plays a role in determining s factors. 

Read More: Howard Gardner’s Theory of Multiple Intelligences in Psychology

Is there a hierarchy? 

The presence of a hierarchical relationship between these factors can be sensed. But it is not as simple. 

  1. The g factor influences the s factor. E.g. A person with a high IQ might have problems grasping mathematical concepts, but it would be easier for him as compared to a person with a low IQ. So, if IQ represents the g factor, the s factor primarily depends on it. 
  2. Methods other than the g factor also influence the s factor. These include training, environment, etc. E.g. A person with a moderate g factor can improve her mathematical abilities by continuous practice. 

Read More: Navigating Fluid and Crystallised Intelligence


  1. Different models of intelligence are proposed by some researchers. Howard Gardner suggests a wide range of autonomous cognitive capacities. Analytical, creative, and practical intelligence are included in Robert Sternberg’s approach. Raymond Cattell differentiates between acquired knowledge and abstract knowledge. 
  2. Spearman believed that the presence of the factor demonstrated a quality of the entire brain, but Thompson saw the construct as a reflection of the functioning of a small number of structures. This difference in perspective led to disagreements on the biological basis of g. 
  3. Spearman’s assessment of particular criteria is not shared by everybody. Some contend that certain skills develop independently of g. 

Read More: Exploring the Many Facets of Intelligence in Children

One may argue that Spearman’s contribution laid the groundwork for the use of mathematical relations in the study of human psychology. While other models suggest fluid/crystallized abilities, various intelligences, or practical skills, the Spearman difference between general and specific thinking is still relevant in the face of criticism.

References +
  • Testbook. (2023, August 10). Spearman Theory of Intelligence: Understanding Intelligence! Testbook. https://testbook.com/ias-preparation/spearman-theory-of-intelligence
  • Crinella, F. M. (1993). Thompson, Lashley, and Spearman: Three views of the Biological Basis of Intelligence. Annals of the New York Academy of Sciences, 702(1), 159–181. https://doi.org/10.1111/j.1749-6632.1993.tb17247.x
  • Charles Spearman and his two-factor theory of intelligence. (2024, January 30). Unacademy. https://unacademy.com/content/upsc/study-material/psychology/charles-spearman/
  • Charles Spearman. (n.d.). https://www.york.ac.uk/depts/maths/histstat/spearman_biog.htm
  • Morgan, C. T., King, R. A., Weisz, J. R., & Schopler, J. (2001). Introduction to psychology (7th ed.). McGraw-Hill. 
  • Ciccarelli, S. K., & White, J. N. (2019). Psychology (5th ed.). Pearson.

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