The type--token ratio in schizophrenic disorders: clinical and research value.

Abstract

Prior research has indicated that the type-token ratio (TTR), a measure of repetition in language, correlates with clinical judgements of thought disorder when spoken language was examined, and differentiates statistically thought-disordered from non-thought-disordered schizophrenics and psychiatric and normal controls. We replicated this finding and examined the clinical sensitivity and specificity of the TTR measure in the diagnosis and in the assessment of thought disorder. The current clinical value of the TTR is limited, but further investigations of the nature of repetition in schizophrenic language are warranted.