Personality as Compressed Social Information in Cooperative Partner Selection

Human cooperation depends on selecting reliable partners under conditions of uncertainty and limited information. I propose that personality traits function as an informational architecture that compresses high-dimensional behavioral observations into low-dimensional representations optimized for prediction and social communication. From this perspective, the Big Five can be understood not merely as a psychometric taxonomy, but as a representational format that facilitates efficient partner choice in cooperative contexts. Compressed trait representations reduce cognitive load, enhance transmission through gossip, and promote reputational consensus. Within this framework, Agreeableness plays a central role in cooperation-dominant settings. I argue that Agreeableness may signal cooperativeness through two complementary mechanisms: by structuring intrinsic cost asymmetries between altruistic and exploitative behavior, and by increasing susceptibility to social learning and norm internalization. This account integrates personality psychology with evolutionary models of partner choice and indirect reciprocity.