In many relationships, a primary goal is to increase intimacy, or relational closeness. Social penetration theory (SPT) explains how partners move from superficial levels to greater intimacy (Altman & Taylor, 1973). SPT uses an onion as a metaphor to describe how relationships move through various stages: just as you might peel off layers of an onion in an attempt to reach the core or center, a relational partner attempts to reach the most intimate thoughts and feelings at the other partner’s “core” (see Figure 7.2).

According to SPT, each layer contains information that is increasingly more private and therefore more risky to divulge to someone else. The outer layer represents aspects of the self that are obvious, such as our appearance, or are surface-level revelations, such as our social categories (male, college student, Texan). Successive layers become more private as partners assess the costs and benefits of the relationship and of disclosing information to each other. If costs exceed rewards, it is unlikely that the partners will move inward toward the more deeply concealed layers. Upon getting to know Jorge, for example, you might find that despite his boisterous exterior, he sometimes suffers from serious bouts of depression, which he manages with medication. But Jorge must choose to reveal this information: it is a part of him that only his closest, most trusted friends know, and he’s likely to reveal it only as a relationship becomes more intimate.