How does the concept of the "unreliable narrator" evolve across different literary periods and genres, and how does this evolution reflect changing societal attitudes towards truth, knowledge, and subjectivity?

This question delves into several key aspects of literary analysis:

• Unreliable Narrators:  How does the portrayal of unreliable narrators change across different literary periods (e.g., Romanticism, Modernism, Postmodernism)? How do these unreliable narrators challenge or reinforce reader expectations?
• Evolving Societal Attitudes:  How do the changing portrayals of unreliable narrators reflect broader societal shifts in attitudes towards truth, knowledge, and the validity of subjective experience?
• Genre and Form:  How does the concept of the unreliable narrator function differently in various genres (e.g., gothic novels, detective fiction, stream-of-consciousness narratives)?