A: (1) Early days (1before the 1920s). 1903, psychologist Thorndike published Educational Psychology. Since then, the book has been expanded to three volumes of Educational Psychology, which laid the foundation for the development of educational psychology, and the name and system of western educational psychology have been established, so Thorndike is called "the father of educational psychology". Thorndike believes that educational psychology is born out of educational needs, and its research direction is to understand and change human nature, so as to achieve educational goals. His three laws of learning and individual difference theory became important topics in educational psychology around the 1920s.

(2) Development period (from 1920s to the end of 1950s). During this period, learning theory has been the main research field. After the 1920s, behaviorism dominated, emphasizing the objectivity of psychology and attaching importance to experimental research. Many factions were formed in this period, and the disputes between these theories and factions were also reflected in educational psychology. The development of educational psychology in this period was divorced from the research route of psychology, lacking an independent theoretical system and research on people's advanced psychological activities. The content is very complicated, but it basically reveals the core. It can be said that educational psychology at this time has not yet become a subject with an independent theoretical system.

(3) Mature period (from 1960s to the end of 1970s). During this period, some changes have taken place in the content and system of western educational psychology. The content of educational psychology has become more and more concentrated, and the discipline system of educational psychology has basically taken shape. The differences among behavioral school, cognitive school and humanistic school are narrowing day by day, and discipline research pays more and more attention to the guidance of school education practice.

(4) Perfect period (post-80s). After 1980s, educational psychology paid more and more attention to the combination with teaching practice, and various theoretical factions absorbed each other and the system became more and more perfect. 65438-0994 American psychologist Bruner summarized the achievements of educational psychology since 1980s: first, active research; second, reflective research; third, cooperative research; fourth, social and cultural research.