Stefan Björk quoted The Haunted Self by Kathy Steele
Integration is on a continuum, with everyone having some degree of integrative impertfection in life. However, not all integrative failure results in structural dissociation. As noted before, trauma-related structural dissociation specifically involves an undue division of or failure to integrate the biopsychosocial systems that together constitute personality. An essential element of this dissociation entails a fragmentation of the sense of self. We normally experience ourselves somewhat differently at work than at play, and very differently as a lover than as a mugging victim, and differently as a child than as an adult. We must integrate these discrepant experiences of ourselves and our world and fashion a rather unitary history from them: "I am the same person who works, plays, loves, and was mugged; I amd an adult and am no longer a child, but am the same person: All these experiences are mine."
A dissociative person does not engage in this degree of integration, at least to an extent. Sometimes structural dissociation may be restricted only to a single traumatizing event, as in simple PTSD, with one extensive ANP and one very limited EP. But the integrative failure may be more extensive for those who were chronically traumatized as children. These children are often deprived of the very developmental tools necessary to develop self-coherence; namely, a sense of self that is unified and singular. [..].
Generally we speak of our "self" as the active agent of integration: "I integrate my experience." But in fact, our "self" does not integrate experience, but rather is the result of integrative actions. [..]. A unified sense of self emerges when we have unconsciously and consciously integrated the many "selves" or "self states" that are a part of normal development [...], and which we suggest are based to a large degree on various (constellations of) action systems and their subsystems and modes. Patients with trauma-related structural dissociation have not been able to engage adequately in the integrative actions that generate and maintain one cohesive sense of self and a cohesive personality.
— The Haunted Self by Kathy Steele, Onno van der Hart, Ellert R. S. Nijenhuis (Page 143)