Reliability and validity study of dokuz eylül theory of mind index

Introduction: Theory of mind, known as the ability to attribute mental states to other people, is a notion that has been widely studied in autism and schizophrenia. However, despite it has been emphasized about the lack of an instrument to asses theory of mind, a reliable and valid index that can asses all aspects of theory of mind doesn?t exist in literature. The aim of this study was to demonstrate validity and reliability of ?Dokuz Eylül Theory of Mind Index? in healthy volunteers and schizophrenia patients, which has been developed from the examples in the literature.Method: Our sample consisted of a total of 285 volunteers, including 197 healthy volunteers and 88 schizophrenia patients who met DSM-IV criteria for schizophrenia. Sociodemographic data form, Dokuz Eylül Theory of Mind Index (DEToMI) and Empathic Skill Index (ESI) were administered to healthy volunteers and patients with schizophrenia.Results: Evidence about reliability and validity of DEToMI in schizophrenia group was founded in this study. Correlation between DEToMI and ESI was not founded in healthy volunteer group (r=0.039, p>0.05); but the correlation in schizophrenia group was r=0.42 (p<0.01). DEToMI has an acceptable internal consistency (0.67); inter rater reliability (r=0.99) and test-retest reliability (r=0.80). And also, high differentiation capacity between healthy volunteers and schizophrenia control group was founded (p<0.05). It has been concluded that DEToMI is a valid and reliable index which can be used in schizophrenia population and the validity of DEToMI must be demonstrated with an other index in healthy volunteer group.Conclusion: Dokuz Eylül Theory of Mind Index has demonstrated psychometric properties in schizophrenia population in this study. Dokuz Eylül Theory of Mind Index would be contributed studies of theory of mind in adult healthy population after its validity study with an other index; and studies of theory of mind and its relationship between schizophrenia and autism symptoms and studies of neural basis of theory of mind.Key Words: Theory of Mind, Theory of Mind Index, schizophrenia, autism.