Theory of mind in schizophrenia and bipolar disorder: psychometric properties of the Norwegian version of the Hinting Task.

ABSTRACTIntroduction: The quality of measures used to assess theory of mind (ToM) in severe mental illness has not been sufficiently investigated. This study evaluated the psychometric properties of the Norwegian version of the Hinting Task in schizophrenia, bipolar I and II disorder and healthy controls.Methods: The study included 90 patients and 183 healthy controls. Internal consistency, ceiling effects, discriminatory power and concurrent and construct validity were investigated.Results: The Hinting Task displayed adequate levels of internal consistency for schizophrenia and bipolar I disorder. Ceiling effects emerged in all groups except the schizophrenia group. Schizophrenia patients scored significantly lower than all other groups, but no other significant group differences were detected. In the schizophrenia group, the Hinting Task's concurrent validity was substantiated by significant correlations with measures of neurocognition, symptoms and functional capacity. In the bipolar disorder groups, however, only a few significant relationships were found. Correlations between the Hinting Task and a measure of emotion recognition indicated that construct validity was higher for schizophrenia than bipolar disorder.Conclusions: The results suggest that the Norwegian Hinting Task is suited for use in schizophrenia research and assessment, but caution is warranted when using the test for other populations.