Edward Thorndike

Edward Lee "Ted" Thorndike (August 31, 1874 – August 9, 1949) was an American psychologist. He spent most of entire career at Teachers College, Columbia University. He worked on ethology and the learning process. This led to the theory of connectionism, and helped lay the scientific foundation for modern educational psychology.
Thorndike also worked on industrial problems, such as employee exams and testing. He was a member of the board of the Psychological Corporation, and served as president of the American Psychological Association in 1912.
Thorndike's law.
The law of effect basically states that “responses that produce a satisfying effect in a particular situation become more likely to occur again in that situation, and responses that produce a discomforting effect become less likely to occur again in that situation”.
Books.
Thorndike's textbooks were widely used in psychology courses for teacher training in the first part of the twentieth century.