The Thought Disorder Index: A reliability study.

Abstract

This article reports interrater reliability among 4 teams of raters who independently evaluated thought disorder in 20 Rorschach protocols using the Thought Disorder Index (TDI). Intraclass correlation coefficients were calculated to assess the degree of association among the 4 teams for total thought disorder scores, severity levels, and qualitative thought disorder factors. Highly ac-ceptable agreement was obtained. Spearman rank order correlation coefficients for these same variables were significant for all possible pairings of teams. A repeated-measures analysis of vari-ance indicated that the absolute amount of thought disorder tagged by each team differed even though the teams ' relative rankings of thought disorder among subjects was very similar. Such scoring differences reflect individual differences in threshold for detecting deviant thinking. Thought disorder has long been regarded as a hallmark of schizophrenia. Kraepelin (1896/1919) described the disor-dered thought processes of schizophrenia as "derailments." Bleuler (1911/1950, 1924) wrote that the central feature of schizophrenic thought was "loosening of associations, " which included associations by contiguity, bizarre and clang associa-tions, as well as condensations of ideas and incoherent dis-course. Subsequent investigations have confirmed the presence of these disorders of thinking in schizophrenic conditions but have also identified thought disorder in patients with affective psychoses, organic brain diseases, and borderline personality