The narrator of Invisible Man himself perfectly exemplifies "outward conformity and inward questioning." The narrator starts his transformation and journey in America's heartland. In his youth, he did not experience the hardships faced by urban African Americans, despite growing up lower-middle class himself. Because he is seen as an outlier among his inner-city black peers in New York City, he feels that it is necessary to conform or adapt to his environment.
Additionally, as someone who did not grow up with the urban experience of his peers, the narrator is eager to adopt their culture and ideologies. He becomes a conformist in this sense, not only because of social pressure from his environment, but also because he feels it is essential to his identity as an African American.
However, this exterior conformity later conflicts with his internal questioning. Like Todd, he conforms to the ideologies and practices of the Brotherhood, but he also becomes fascinated with other revolutionary ideas, such as the Neo-African nationalism preached by Ras. The psychological basis for the narrator's conformity is his need to adapt in order to gain an identity.
Therefore, the narrator can easily conform to a culture but just as easily leave it to conform to a new one. In essence, this is why he is the "invisible" man. He embodies the diverse characteristics and experiences of the 20th-century (and contemporary) African American citizen, and yet he is not one particular entity.