Irregular assimilation progress: reasons for setbacks in the context of linguistic therapy of evaluation.

The assimilation model suggests progress in psychotherapy follows an eight-stage sequence described by the Assimilation of Problematic Experiences Scale (APES). This study sought to reconcile this developmental stage model with the common but superficially contradictory clinical observation that therapeutic advances alternate with setbacks. Setbacks (n=466) were identified in therapy transcripts of two clients and classified using a preliminary nine-category list of possible alternative reasons for setbacks. Most of the setbacks involved switches among the multiple strands of a problem due to (a) therapists exceeding clients' therapeutic zone of proximal development, (b) therapists guiding clients to shift toward relatively problematic material (balance metaphor), or (c) spontaneous switches. Rather than contradicting the theory, this close examination of setbacks yielded elaborations of it.