How did the field of psychology develop?

Many trace the development of psychology to diverse philosophers that date back to over a thousand years before the common era and encompass traditions that stretch from Greek, to Persia, to China, to Egypt, to India. However, the history of psychology as an institutionalized discipline in the (modern) academy has a shorter history and is conventionally affiliated with the experimental studies of Wilhelm Wundt in the year of 1879 - who started the first psychology research lab at the University of Leipzig in Germany. Along with experimental psychology the emergence of the field was closely knit with a particularly applied practice and the specific space of the clinic beyond the research lab of the academy. Early goals of the field were both to generate explanations of mental differences (associated with the practices of classification and quantification - e.g. anthropometrics and psychometrics- such as the work of Sir Francis Galton) and to cure/heal/treat abnormal or pathological psyches or mental dispositions (associated with the practices of interpreting the unconscious - e.g. psychoanalysis - such as the work of Sigmund Freud). By the 20th century new schools of thought rose to prominence, such as behaviorism (and the work B.F. Skinner and Ivan Pavlov) - which prioritized empirically observable behavior -- e.g. what the body did -- over speculations on the mind. The next wave of thought that transformed the field is known as humanistic psychology (associated with the work of Abraham Maslow and Carl Rogers), which concerned itself with understanding the human experience -- and the power of free-will and self-determination. Today, the field has a range of faces from developmental to cognitive to social psychology, all of which are layered on top of and interpenetrated by the rich traditions and legacies that proceed them and laid the foundation of the discipline.