A Comparison of Clinical and Linguistic Indices of Deviance in the Verbal Discourse of Schizophrenics.

The goal of this study was to compare clinical and psycholinguistic approaches to the measurement of verbal behavior according to their ability to discriminate schizophrenic ( n = 11) from manic-depressive ( n = 11) and normal control ( n = 11) subjects. Language samples were obtained during Rorschach testing and analyzed using a clinical measure, the Thought Disorder Index (TDI), and a battery of linguistic measures. Five linguistic categories were examined: productivity, repetition, dysfluency, cohesiveness, and syntactic complexity. On the clinical measure, schizophrenic subjects had high thought disorder scores. On the linguistic measures, the speech of schizophrenics differed significantly from the other two groups in productivity and in the number of clearly referenced elements, a measure of cohesion. This measure of cohesion was positively correlated with TDI scores. The findings are discussed in terms of the benefits of using more objective and quantitative measurements in research on thought disorganization in schizophrenia.