Wilhelm Wundt provided a complete and concise description of his introspective method in a 1907 paper criticizing the thought experiments conducted by the Wurzburg psychologists. This major work is now being translated for the first time. For Wundt, the role of experimental method was to ensure the best conditions for observing and reporting conscious experiences, with the aim of gathering reliable results upon which a systematic science of consciousness could be erected. Wundt had four rules for correct introspective practice: (1) the introspective observer must be able to decide for himself at what point to begin observing the mental process under investigation; (2) the observer must be in a state of heightened attention; (3) each observation must be repeated again and again under the same conditions; and (4) circumstances under which the phenomenon occurs must be investigated by varying the accompanying experimental situations. Wundt's rules and practices for scientific introspection are related to contemporary debates in cognitive science over the nature and proper use of introspection. Current critiques of introspective methods for investigating thinking were anticipated by Wundt in 1907. (Author/ABL)