Abstract
The impact of internal responsivity factors and therapeutic process variables on intra-individual within-treatment gain in sex offenders has received little empirical attention. This study examined how (1) internal responsivity factors, including treatment readiness and interpersonal style, and (2) therapy process variables, including the therapeutic alliance and the presence of ruptures in the therapeutic relationship, impacted intra-individual within-treatment gain. Participants comprised 71 sex offenders who participated in group-based sex offender treatment programmes in prison or the community. Results showed that offender hostile-dominance and the affective and interpersonal characteristics of psychopathy, as measured by the Psychopathy Checklist: Screening Version Factor 1 score, negatively impacted treatment gain. Pre-treatment readiness, client ratings of the therapeutic alliance and whether or not there were ruptures in the therapeutic relationship had no association with within-treatment gain. The strength of the therapeutic alliance later in treatment did not moderate the relationship between offender interpersonal style, or psychopathy, and treatment gain.