SPT states that the relationship development occurs primarily through self-disclosure, or intentionally revealing personal information such as personal motives, desires, feelings, thoughts, and experiences to others. Today, this remains the building block of relationship theory. This theory assumes that as one becomes closer, positive reinforcement through positive interactions will allow one to go into deeper levels of intimacy. This theory is also guided by the assumptions that relationship development is systematic and predictable. Through self-disclosure, relationship development follows particular trajectory, moving from superficial layers of exchanges to more intimate ones. Self-disclosure is the major way to bring a relationship to a new level of intimacy. SPT also examines the process of de-penetration and how some relationships regress over time and eventually end.