Intelligence researchers

William Stern (born Ludwig Wilhelm Stern; April 29, 1871 – March 27, 1938) was a German psychologist and philosopher who originated personalistic psychology, which placed emphasis on the individual by examining measurable personality traits as well as the interaction of those traits within each person to create the self.
Stern coined the term intelligence quotient (IQ) and invented the tone variator as a new way to study human perception of sound. Stern studied psychology and philosophy under Hermann Ebbinghaus at the University of Berlin, and quickly moved on to teach at the University of Breslau. Later he was appointed to the position of professor at the University of Hamburg.
Over the course of his career, Stern authored many books pioneering fields of psychology such as differential psychology, critical personalism, forensic psychology, and intelligence testing. Stern was also a pioneer in the field of child psychology. Together with his wife, Clara Joseephy Stern, the couple kept meticulous diaries detailing the lives of their 3 children for 18 years. He used these journals to write several books that offered an unprecedented look into the psychological development of growing children.

Alfred Binet (French: [binɛ]; 8 July 1857 – 18 October 1911), born Alfredo Binetti, was a French psychologist who invented the first practical IQ test, the Binet–Simon test. In 1904, the French Ministry of Education asked psychologist Alfred Binet to devise a method that would determine which students did not learn effectively from regular classroom instruction so they could be given remedial work. Along with his collaborator Théodore Simon, Binet published revisions of his test in 1908 and 1911, the last of which appeared just before his death.