Researchers have focused on how different family dyads, such as parent-child, sibling, and romantic relationships, negotiate conflictual interactions. It is the conflict experienced by the romantic couple that is of particular import to this chapter, namely, a marital process cascade known as the Four Horsemen of the Apocalypse. One scholar, clinical psychologist John Gottman, has devoted his entire career to understanding the anatomy of couple conflict. Gottman's "social psychophysiological approach" to the topic is firmly grounded in the postpositivist tradition of inquiry. Gottman also originally identified two types of unstable, non-regulated couples: hostile and hostile-detached. The key component that distinguishes contempt, the second horseman, from criticism is the "intention to insult and psychologically abuse your partner". After contempt, the third horseman, defensiveness, makes an appearance. The fourth and final horseman of this communicative process is stonewalling, or withdrawing from the other person.