Titchener was aware of the possible effects of bias, as well as of faulty memory, on introspection. But he believed that the problem with bias can be remedied by preparing relatively simple tasks, by exercising strict standardization, and by extensively repeating the task within and between subjects. As for the problem with faulty memory, Titchener acknowledged that introspection is the similar with retrospection. Titchener's version of introspection is similar to Wundt's idea of self-observation. And since Wundt denied self-observation a spot in his laboratory because of its being highly susceptible to bias, he also rejected Titchener's systematic experiment introspection. Caution must be exercised to avoid taking Wundt's introspection to be a single idea, instead of it being split to internal perception and self-observation. Caveat, also, in taking Wundt's introspection and Titchener's systematic experiment introspection to be the same.

Wundt used introspection (specifically internal perception) as a primary tool in his then-newly-established experimental psychology since it provided a way to tap an individuals' cognition - an entity not directly observable, and was once thought by some to be impossible to observe. Introspection served as a tool in understanding mental processes,...

With introspection, it became possible to scrutinize not only the physical event, but also the event's mental counterpart.
Because of introspection, much insight has been gathered regarding the human mind and how it works. Introspection triggered more studies and thus, resulted to a wealth literature. Some studies have set forth to provide support to introspection, while others to highlight its weaknesses and limitations. Whichever is the case, it cannot be denied that introspection spawned more research works and served as basis for more tools in understanding the human mind; thus, taking knowledge to greater heights. Thanks to William Wundt, for believing and showing the world that Experimental Psychology is a valid field of Psychology.

References

Davis, Stephen F. (Ed.). (2003). Handbook of Research Methods in Experimental Psychology. Malden, UK: MA Blackwell Publishing Ltd.

Reiber, R.W. & Robinson, D.K. (Eds.). (2001). Wilhelm Wundt in History: The Making of a Scientific Psychology. NY: Kluwer Academic Publishing.

David, Zehr. (2000). Portrayals of Wundt and Tichener in introductory psychology texts: a content analysis. Teaching of Psychology, 27 (2), 122-126.