Martijn van Teffelen

ABSTRACT Hostility is a transdiagnostic phenomenon that can have a profound negative impact on interpersonal functioning and psychopathological severity. Evidence suggests that cognitive bias modification for interpretation bias (CBM-I) potentially reduces hostile interpretation bias (HIB), anger, and aggression. However, stringent efficacy trials in people with clinical levels of hostility are currently lacking. The present study investigated the effects of CBM-I in two studies: one randomized sham-controlled feasibility trial (Study 1) in a mixed clinical-community sample of men ( N = 20), and one randomized sham-controlled clinical trial (Study 2) in a mixed- gender sample with clinical levels of hostility ( N = 135), pre-registered at https://osf.io/r46jn. We expected that CBM-I would result in a larger increase in benign bias and larger reductions in hostile bias, hostility symptoms and traits at post-intervention compared to an active control (AC) condition. We also explored beneficial carry-over effects of CBM-I on working alliance in subsequent psychotherapy five weeks after finishing CBM-I ( n = 17). Results showed that CBM-I increased benign bias in both trials and reduced HIB in Study 2, but not in Study 1. Findings of Study 2 also revealed greater reductions in behavioral aggression and less reductions in general psychological distress in CBM-I relative to control, though no condition differences were found in self-report hostility measures. The results suggest that CBM-I is an efficacious intervention for HIB and aggressive behavior.