Partly as a result of Titchener's misrepresentation, the use of introspection diminished after his death and the subsequent decline of structuralism. Later psychological movements, such as functionalism and behaviorism, rejected introspection for its lack of scientific reliability among other factors.

What was the major weakness of introspection?

Introspection is limited in its use; complex subjects such as learning, personality, mental disorders, and development are difficult or even impossible to study with this technique. The technique is difficult to use with children and impossible to use with animals.

What makes introspection a poor way to study psychology?

Introspection is problematic for studying cognitive tasks because it was limited as a research tool since some thoughts are unconscious and since introspection is the study that consists of conscious experiences it cannot tell us anything about unconscious events.