Influenced by Brentano’s act psychology, Carl Stumpf was Wundt’s major rival. Although he restricted his work to space perception and audition, Stumpf’s laboratory at the University of Berlin was a serious competitor to Wundt’s lab at the University of Leipzig.
Like Wundt, Stumpf used introspection as his primary method of investigation. Unlike Wundt, Stumpf didn’t require his assistants to be trained introspectionists. When researching the psychology of music, for example, Stumpf preferred trained musicians over trained introspectionists.
In a series of articles, Wundt and Stumpf argued the matter. Although it began as a theoretical discussion, it deteriorated into a personal, bitter dispute. The dispute may have been a continuation of their battle for a prestigious job (when Stumpf was selected over Wundt to follow Helmholtz at the University of Berlin).