Psychological evaluation
Modern "Psychological evaluation" has been around for roughly 200 years, with roots that stem as far back as 2200 B.C. It started in China, and many psychologists throughout Europe worked to develop methods of testing into the 1900s. The first tests focused on aptitude. Eventually scientists tried to gauge mental processes in patients with brain damage, then children with special needs.
The Principles of Psychology
"The Principles of Psychology" was a vastly influential textbook which summarized the field of psychology through the time of its publication. Psychology was beginning to gain popularity and acclaim in the United States at this time, and the compilation of this textbook only further solidified psychology's credibility as a science. Philosopher Helmut R. Wagner writes that most of the book's contents are now outdated, but that it still contains insights of interest.