James studied closely the schools of thought known as associationism and spiritualism. His conclusions were largely based on ideas of associationism. For Fodor, this position emerges naturally out of his criticism of behaviourism and associationism. Among the earliest experiments that tested the applications of associationism involve Hermann Ebbinghaus' work. Erasmus Darwin based his theories on David Hartley's psychological theory of associationism. In the late 1830s Ripley became increasingly engaged in "Associationism", an early Fourierist socialist movement. To place this trust in someone else leads to the greatest sin, shirk ("hidden associationism"). James combined the views of spiritualism and associationism to create his own way of thinking. Like Ward, Stout employed a philosophical approach to psychology and opposed the theory of associationism. Whereas in associationism, ideas and behaviors are separate, in spiritualism, they are connected. James disagreed with associationism in that he believed it to be too simple. Associationism is often concerned with middle-level to higher-level mental processes such as learning.