Spock

"It is a peculiar sensation, this double-consciousness, this sense of always looking at one’s self through the eyes of others, of measuring one’s soul by the tape of a world that looks on in amused contempt and pity. One ever feels his two-ness [...] two souls, two thoughts, two unreconciled strivings; two warring ideals in one body, whose dogged strength alone keeps it from being torn asunder.

[...] this longing to attain self-conscious manhood, to merge his double self into a better and truer self. In this merging he wishes neither of the older selves to be lost. [...] He would not bleach his blood, for he knows that his blood has a message for the world. He simply wishes to make it possible for a man to be both [...] without being cursed and spit upon by his fellows, without having the doors of opportunity closed roughly in his face."

-W.E.B. DuBois

A large part of Spock's characterization is informed by a struggle with a multi-faceted conception of self. This was exacerbated by being torn from a homeland and being forced to struggle to choose how to define himself. He is a member of a largely human Starfleet but he is not always treated the same.

As a member of a largely human organization and crew, he must define himself not only through his own eyes but through the eyes of a human other; thus, a constant awareness of how much his own sense of identity - from being raised chiefly Vulcan - conflicts with his own human sense of identity and value which is now being imposed on him by his peers.

He must struggle for his psycho-social world to yield a true self-consciousness, so that he can see himself beyond the revelation of being both an outsider and an insider at once.

His behavior is often over-compensating and Vulcan more often than human because he was raised on Vulcan, but he is still looking at each side of himself through the eyes of the other. The human Spock views the Vulcan Spock with contempt, and the Vulcan Spock views the human Spock with pity. Each is often distorted by the negative cultural image of the other race.

Because he seeks normative judgement in his own thinking so heavily, he measures either side of his soul with the tape of the other.