Parataxical integration exists when two people, usually intimate with each other (i.e. parents and children, spouses, romantic partners, business associates), are reciprocally reactive to each other's seductions, judgmental inaccuracies, hostile comments, and manipulations or other "triggering" behaviors.
Parataxical integrations are also presented in similar studies reported by Ronald D. Laing, Aaron Esterson, and anthropologist Jules Henry, largely during the 1950s and 1960s.
Rodger Garrett also employs the concept in his millennial-era work on borderline personality disorder and family of origin etiology, typically using the term "reciprocal reactivity" along with it.
Reciprocal reactivity was studied by Gary Sperduto et al. in the 1970s, and it is clear from the abstract of his paper (see below) that his definitional terminology equated to that of Sullivan.
Numerous mass-market psychology authors, many writing about the topic of "co-dependence," including Melody Beattie, Pia Mellody, Anne Wilson Schaef, and Barry & Janae Weinhold, describe the interpersonal manifestation without using Sullivan’s term per se.