There is still a need for evidence based explanations for how or why psychotherapy works. Even though a large amount of theoretical contributions about effectiveness based on clinical experience exists, a gap seems to still be present between this knowledge and the operationalizations of theoretical concepts that can generate empirical knowledge to guide treatment. Consequently, the overall focus of this thesis has been to investigate in more detail relevant phenomena contributing to processes of change in psychotherapy.
The aim for Paper I was to investigate the psychometric properties of the observational psychotherapy process instrument Achievement of Therapeutic Objectives Scale (ATOS) with the use of Generalizability Theory and to test whether trained raters could produce dependable observations. This was particularly important aspect to clarify since the ATOS was used to perform observational ratings of about 1000 sessions of short-term dynamic (STDP) and cognitive (CT) psychotherapy from the Svartberg, Stiles and Seltzer (2004) RCT study, including 50 patients with cluster C personality disorder diagnoses. Within this sample of patients, a further aim was to investigate the influence of affects as possible important phenomena for change in levels sense of self and others towards more compassionate and realistic qualities (presented in paper II). Then, we investigated whether change towards more compassionate and realistic qualities of sense of self and others across psychotherapy predicted co-varying improvement in various interpersonal relational problems for patient receiving either STDP or CT treatment (presented in paper III).
The results of the thesis provided evidence for ATOS being a psychometrical sound process instrument with raters producing dependable observations. Further, levels of experienced affects across therapy were relevant for the development of a sense of self and others towards more compassionate and realistic quality. Particularly, increased levels of adaptive affects within a therapy session predicted increase in levels of sense of self and others the next session. Then, higher levels of realistic and compassionate sense of self and others were found to be helpful in reducing interpersonal problems known to be particularly difficult for persons diagnosed with cluster C personality disorders, however these effects were only present within the STDP treatment condition.