This paper undertakes to answer the questions of how humanness is to be defined and computationally functionalized, as well as of how person-situation interaction is to be formalized mathematically. Complexity science and psychoinformatics are the two primary fields considered in addressing these questions. A novel "psychoinformatic complexity" (PIC) paradigm is outlined and argued to be an adequate one within which to operationalize modern-day Western humanness and person-situation interaction. The paper ends with a consideration of current PIC applications, including social media analytics and humanoid robotics.