Many psychologists have influenced thoughts and given an insight into the psyche. Charles Edward Spearman was a psychologist in London, England born September 10, 1863 and died September 17, 1945 in London. He spent some time as a British officer, and during this time, Spearman came to believe that any vital progress in philosophy would be linked to psychology. He spent ten years at the University of Leipzig, working with others like Wilhelm Windt, the founder of experimental psychology. Spearman tried to start general fundamental laws of psychology. It was supported through his work in determining correlations among mental abilities. He spent time interpreting correlations among lots of variables on the foundation of a specific factor for each variable and a factor common to all. By 1912, he and a colleague developed an order of correlation coefficients separating the numerous acts into the general factor, g, and varying particular factors, s1, s2, and so on. The more in depth descriptions of his work are found in the Abilities of Man in 1927. .
Intelligence is defined as the ability to gain and use knowledge in a useful way. Spearman introduced the scientific method to intelligence testing. He examined and evaluated intelligence in a logical way. He believed that in time researchers would be able to figure out all the variables that fueled the levels of intelligence, and how the variables fit together. During Spearman's time the Pearson Correlation test came about; it was designed to illustrate whether one part of human capability was related from one test next to the results of another test. Charles Spearman was not convinced with Pearson's test. He felt the difficulty with the test was not in data and the results, but in its process of analysis. He figured out that Pearson's statistics miscalculated the strength of correlation that linked the results of the two tests. Spearman fixed this concern by inventing a new statistical procedure that is called the Spearman Rank Order Correlation.