Charles Spearman

Charles Spearman played a pivotal role in exploring human intelligence. Human intelligence is a subjective topic, and when you ask people, “what is intelligence?” The answers will vary because understanding intelligence is difficult. For example, for some people, an intelligent person will be the one who solves mathematics questions quickly, while for others, an intelligent person will be a person who makes accurate life decisions.

Giving a proper definition of intelligence has been debatable. Different psychologists have different views on intelligence. If we have to come up with a comprehensive definition of intelligence, it can be said that intellect is a tangible process that involves parameters such as planning, attention, learning and solving.

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About Charles Edwards Spearman

Charles Edward Spearman was a well-known British psychologist born on 10th September 1863. He showed exceptional talent and capability to become a psychologist since his inception. He began his career by joining the British army, and he served them for 15 years. After his retirement from the army, he decided to pursue a PhD in Experimental Psychology. He went to the University of Leipzig, Germany, because the institute had liberal entrance policies under Wilhelm Wundt.

Charles Spearman is considered the epitome of factor analysis. He was the first to use mathematical methods to analyse and interpret the twisted human brain. Moreover, He was responsible for the discovery of general intelligence, also known as the “g factor” with the help of factor analysis. He was able to announce intelligence as a cognitive ability that is measurable. Thus it can be explained using numbers.

Using factor analysis, Spearman was able to prove the theory of general intelligence. According to the psychologist, a person who is able to solve more questions on an aptitude test has a higher intelligence when compared to a person who is able to solve lesser questions.

The psychologist invented Spearman’s rank correlation coefficient to prove his hypothesis. The Spearman correlation coefficient is implemented for measuring the statistical dependency between a couple of variables (‘g’ factor and ‘s’ factor)

The two-factor theory of intelligence

Charles Spearman published his two-factor theory of intelligence in the year 1904. He was the founding person of the concept of general intelligence called the “g” factor. He analysed different mental aptitude and cognitive tests attempted by the participants to form this theory.

While evaluating the tests, he identified that scores of the same participants were similar in every test. That is,  a person who scored high marks in one aptitude test scored the same marks in other aptitude tests as well. On the contrary, the person who scored low marks on one aptitude test scored lower marks on the other aptitude tests as well. Thus, he came to the conclusion that there is a factor between the intellect and cognitive abilities of a person.

He employed the factor analysis technique to examine the cognitive tests. After examining the tests, he concluded that the factors related to intelligence could be expressed numerically. Thus he proposed that the various mental traits are not independent of each other, and there exists a factor called the general factor or “g” factor.

“G” and “S” factors of two-factor theory

Spearman proposed that intelligence consists of two factors which are the “g” factor and “s” factor. The “g” factor is linked to the general ability, while the “s” factor is linked to the specific ability. The “g” factor reflects the capability of a person in doing the general mental ability tasks, and the “s” factor is responsible for recognizing the specific abilities of a person.

Moreover, the name “two-factor theory” doesn’t indicate that there are only two factors. There are more than two factors in the theory because each factor has different sub-factors, which depend on the number of specific abilities in each test.

According to psychologist, the specific abilities of the person can be drawing interference, coding abilities, mathematical abilities, etc.

Spearman’s rank correlation coefficient

In statistics, the coefficient of correlation, which is named after Charles Spearman, is represented using “rho”. This is a non-parametric measure of correlation; the factor analyses the effectiveness of an arbitrary in describing the connection between variables without taking into consideration the frequency distribution of variables. The coefficient doesn’t demand a linear relationship between variables, and neither does it need the variables to be measured in interval scales.

The Spearman correlation coefficient is a derivative of the product-moment coefficient. In the product-moment coefficient, the data is converted to ranks before calculating the coefficient. However, in practice, simpler means are used to calculate the correlation coefficient. The preliminary scores obtained after calculation are converted into ranks. After this, a difference between the D and ranks of every observation is determined using the formula below.

In this formula,

D= Difference between values of X and Y

N= Pairs of the value of X and Y

Calculating the Spearman correlation coefficient becomes more complex if the tied ranks are present. However, if the bends are large, ignoring them becomes difficult.

Conclusion

Charles Spearman is a personality whose work has motivated other psychologists such as Hans Eysenck, Philip Vernon, Cyril Burt and Arthur Jensen. However, out of all the people he has influenced, his strongest admirer is Francis Galton. Francis Galton was the first to discover the correlation tool as a statistical tool in psychology.

Spearman’s accomplishment can be regarded as the foundation for studying human psychology using mathematical relations. Charles Spearman will always be an influential person. He lived a large life and passed away on 17th September 1945 in London, United Kingdom.

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