Gustav Fechner
Fechner, along with Wilhelm Wundt and Hermann von Helmholtz, is recognized as one of the founders of modern experimental psychology. His clearest contribution was the demonstration that because the mind was susceptible to measurement and mathematical treatment, psychology had the potential to become a quantified science. Theorists such as Immanuel Kant had long stated that this was impossible, and that therefore, a science of psychology was also impossible.
Lawrence Kohlberg
Lawrence Kohlberg (; October 25, 1927 – January 19, 1987) was an American psychologist best known for his theory of stages of moral development. He served as a professor in the Psychology Department at the University of Chicago and at the Graduate School of Education at Harvard University. Even though it was considered unusual in his era, he decided to study the topic of moral judgment, extending Jean Piaget's account of children's moral development from twenty-five years earlier. In fact, it took Kohlberg five years before he was able to publish an article based on his views. Kohlberg's work reflected and extended not only Piaget's findings but also the theories of philosophers George Herbert Mead and James Mark Baldwin. At the same time he was creating a new field within psychology: "moral development". In an empirical study using six criteria, such as citations and recognition, Kohlberg was found to be the 30th most eminent psychologist of the 20th century.