His chief method of investigation was introspection; he asked participants to look inwards and then describe how they saw their minds as functioning. Special training was supposed to make them more complete and careful in their observations, and to prevent them from interpreting their own minds too much. This experimental introspection was in contrast to what had been called psychology until then, a branch of philosophy where people introspected themselves, rather than being studied by a psychologist.
Wundt subscribed to a "psychophysical parallelism" (which entirely excludes the possibility of a mind-body/cause-effect relationship), which was supposed to stand above both materialism and idealism.
Titchener, a two-year resident of Wundt's lab and one of Wundt's most vocal "proponents" in the United States, is responsible for several English translations and mistranslations of Wundt's works that supported his own views and approach, which he termed structuralism and claimed was wholly consistent with Wundt's position.