 When his involvement with hypnosis waned as a result of failure to establish professional acceptance, he turned to the study of development spurred on by the birth of his two daughters, Marguerite and Armande (born in 1885 and 1887, respectively), calling Armande a subjectivist and Marguerite an objectivist, and developing the concepts of "introspection" and "externospection" in an anticipation of Carl Jung's psychological types.In the 21-year period following his shift in career interests, Binet "published more than 200 books, articles, and reviews in what now would be called experimental, developmental, educational, social, and differential psychology.