Louis Thurstone was an American psychologist and psychometrician, born in 1887. He is best known for his work in the field of intelligence testing and for developing the Thurstone's primary mental abilities theory, which proposed that intelligence is made up of several distinct factors rather than a single general ability. His research significantly influenced the way intelligence is measured and understood. Thurstone also contributed to the development of factor analysis, a statistical method used to identify underlying relationships between variables. Throughout his career, he published numerous articles and books, helping to advance the fields of psychology and education. He passed away in 1955, leaving a lasting legacy in psychometrics.