Measuring change in depression-related interpretation bias: development and validation of a parallel ambiguous scenarios test.

Depressed mood is associated with making negatively biased interpretations of ambiguous everyday events. Experimental modification towards a more optimistic interpretation has become a focus of recent research. However, to date, no measures exist that have been tested with respect to their psychometric properties that justify repeated administration to capture change. We aimed to develop and evaluate a pragmatic assessment instrument, consisting of a 30-item questionnaire (long version) and two 15-item parallel short versions (A and B). Items were generated as ambiguous sentences, reflecting three relevant content areas based on Beck's cognitive triad. The sentences were rated for pleasantness, and this emotional appraisal task indicates the emotional valence of the interpretation. Due to the intention to develop a parallel test version, item-twins were generated. All three versions of the instrument were found to be structurally stable, internally consistent and valid. In line with Beck's cognitive triad in depression, confirmatory factor analyses determined a three-factor solution (i.e. self, experiences and future). Significant correlations were found between all scales and depressive mood. The two short versions represent the same underlying constructs, share identical psychometric properties and possess high parallel-test reliability. This study is the first to evaluate and confirm the factorial validity as well as the parallel-test reliability of an interpretation bias measure. It is suitable to measure bias modification and has therefore great potential for research and clinical practice.