Functional psychology or functionalism refers to a psychological school of thought that was a direct outgrowth of Darwinian thinking which focuses attention on the utility and purpose of behavior that has been modified over years of human existence. Edward L. Thorndike, best known for his experiments with trial-and-error learning, came to be known as the leader of the loosely defined movement. This movement arose in the U.S. in the late 19th century in direct contrast to Edward Titchener's structuralism, which focused on the contents of consciousness rather than the motives and ideals of human behavior. Functionalism denies the principle of introspection, which tends to investigate the inner workings of human thinking rather than understanding the biological processes of the human consciousness. While functionalism eventually became its own formal school, it built on structuralism's concern for the anatomy of the mind and led to greater concern over the functions of the mind and later to the psychological approach of behaviorism. History Functionalism was a philosophy opposing the prevailing structuralism of psychology of the late 19th century. Edward Titchener, the main structuralist, gave psychology its first definition as a science of the study of mental experience, of consciousness, to be studied by trained introspection. At the start of the nineteenth century, there was a discrepancy between psychologists who were interested in the analysis of the structures of the mind and those who turned their attention to studying the function of mental processes. This resulted in a battle of structuralism versus functionalism. The main goal of Structuralism was to make attempts to study human consciousness within the confines of an actual living experience, but this could make studying the human mind impossible, functionalism is in stark contrast to that. Structural psychology was concerned with mental contents while functionalism is concerned with mental operations. It is argued that structural psychology emanated from philosophy and remained closely allied to it, while functionalism has a close ally in biology. William James is considered to be the founder of functional psychology. But he would not consider himself as a functionalist, nor did he truly like the way science divided itself into schools. John Dewey, George Herbert Mead, Harvey A. Carr, and especially James Rowland Angell were the main proponents of functionalism at the University of Chicago. Another group at Columbia, including notably James McKeen Cattell, Edward L. Thorndike, and Robert S. Woodworth, were also considered functionalists and