Cati Brown

Schizophrenia and the structure of language: The linguist's view

Patients with schizophrenia often display unusual language impairments. This is a wide ranging critical review of the literature on language in schizophrenia since the 19th century. We survey schizophrenic language level by level, from phonetics through phonology, morphology, syntax, semantics, and pragmatics. There are at least two kinds of impairment (perhaps not fully distinct): thought disorder, or failure to maintain a discourse plan, and schizophasia, comprising various dysphasia-like impairments such as clanging, neologism, and unintelligible utterances. Thought disorder appears to be primarily a disruption of executive function and pragmatics, perhaps with impairment of the syntax-semantics interface; schizophasia involves disruption at other levels. Phonetics is also often abnormal (manifesting as flat intonation or unusual voice quality), but phonological structure, morphology, and syntax are normal or nearly so (some syntactic impairments have been demonstrated). Access to the lexicon is clearly impaired, manifesting as stilted speech, word approximation, and neologism. Clanging (glossomania) is straightforwardly explainable as distraction by self-monitoring. Recent research has begun to relate schizophrenia, which is partly genetic, to the genetic endowment that makes human language possible.

Automatic measurement of propositional idea density from part-of-speech tagging

The Computerized Propositional Idea Density Rater (CPIDR, pronounced “spider”) is a computer program that determines the propositional idea density (P-density) of an English text automatically on the basis of partof-speech tags. The key idea is that propositions correspond roughly to verbs, adjectives, adverbs, prepositions, and conjunctions. After tagging the parts of speech using MontyLingua (Liu, 2004), CPIDR applies numerous rules to adjust the count, such as combining auxiliary verbs with the main verb. A “speech mode” is provided in which CPIDR rejects repetitions and a wider range of fillers. CPIDR is a user-friendly Windows .NET application distributed as open-source freeware under GPL. Tested against human raters, it agrees with the consensus of two human raters better than the team of five raters agree with each other [r(80) = .97 vs. r(10) = .82, respectively].

Does ketamine mimic aspects of schizophrenic speech

Speech disturbances are well-known symptoms contributing to the diagnosis of schizophrenia. Subanesthetic doses of the N-methyl-D-aspartate (NMDA) antagonist ketamine have been reported to produce positive and negative symptoms and cognitive impairments consistent with those seen in schizophrenia. Insofar as this is true, it constitutes evidence that the NMDA system is involved in schizophrenia. It is therefore of interest to know whether ketamine produces speech disturbances like those of schizophrenia. Quantitative computer-aided analysis of apparently normal speech can detect clinically relevant changes and differences that are not noticeable to the human observer. Accordingly, in this study, speech samples were analysed for repetitiousness, idea density, and verb density using software developed by the authors. The samples came from two experiments, a within-subjects study of healthy volunteers given intravenous ketamine versus placebo, and a between-groups study of patients diagnosed with schizophrenia and comparable healthy controls. Our primary hypothesis was that in both schizophrenia and ketamine, repetitiousness wouLd increase, since perserverative speech is a well-known symptom of schizophrenia. Our secondary hypotheses were that in both schizophrenia and ketamine, idea density and verb density would decrease as indicators of cognitive impairment. The primary hypothesis was confirmed in the schizophrenia experiment (between groups) and the ketamine experiment (within subjects). The secondary hypotheses were disconfirmed except that in the ketamine experiment, verb density was significantly lowered. Reduced use of verbs apparently reflects a cognitive impairment of a different type than repetitiousness, and further investigation is needed to determine whether this impairment occurs in psychosis.

Looking for the Smoking Gun: Principled Sampling in Creating the Tobacco Industry Documents Corpus

As a result of litigation over the past decade, major tobacco companies were compelled to make public a broad range of previously confidential documents. We have created a series of corpora from the tobacco industry documents (TIDs) for three purposes: (1) to establish baseline descriptions of various linguistic features of this unique set of texts; (2) to identify TIDs in which rhetorical manipulation (“deception”) may have occurred and to estimate the extent and prevalence of manipulation; (3) to analyze manipulation in order to classify it and develop means to identify similar manipulation in other industry document sets. Our threepart corpus creation strategy employed rigorous sampling methods. First, we drew a limited sample from the largest collection of TIDs, to determine a representative classification of text types and to estimate their proportions within the overall body of texts. Then, we created a reference corpus (500,000+ words) constituting a stratified random sample of all TIDs, whether or not they exhibit manipulation. Finally, we compiled a corpus of texts presumed to exhibit rhetorical manipulation. We assumed that multiple drafts of a text or versions of a text prepared for different audiences constituted rhetorical manipulation. This article presents our experience with the sampling methods utilized in this corpus-building process and our findings regarding text types comprising the reference corpus.As a result of litigation over the past decade, major tobacco companies were compelled to make public a broad range of previously confidential documents. We have created a series of corpora from the tobacco industry documents (TIDs) for three purposes: (1) to establish baseline descriptions of various linguistic features of this unique set of texts; (2) to identify TIDs in which rhetorical manipulation (“deception”) may have occurred and to estimate the extent and prevalence of manipulation; (3) to analyze manipulation in order to classify it and develop means to identify similar manipulation in other industry document sets. Our threepart corpus creation strategy employed rigorous sampling methods. First, we drew a limited sample from the largest collection of TIDs, to determine a representative classification of text types and to estimate their proportions within the overall body of texts. Then, we created a reference corpus (500,000+ words) constituting a stratified random sample of all TIDs, whether or not they exhibit manipulation. Finally, we compiled a corpus of texts presumed to exhibit rhetorical manipulation. We assumed that multiple drafts of a text or versions of a text prepared for different audiences constituted rhetorical manipulation. This article presents our experience with the sampling methods utilized in this corpus-building process and our findings regarding text types comprising the reference corpus.

Ketamine and schizophrenic speech: more difference than originally reported.

MA Covington CASPR, Artificial Intelligence Center, University of Georgia, Athens, GA, USA. WJ Riedel Department of Neuropsychology and Psychopharmacology, Faculty of Psychology, University of Maastricht, The Netherlands. C Brown CASPR, Artificial Intelligence Center, University of Georgia, Athens, GA, USA; H5, San Francisco, CA, USA. C He CASPR, Artificial Intelligence Center, University of Georgia, Athens, GA, USA. E Morris CASPR, Artificial Intelligence Center, University of Georgia, Athens, GA, USA. S Weinstein Department of Psychiatry, University of British Columbia, Vancouver, BC, Canada. J Semple CASPR, Artificial Intelligence Center, University of Georgia, Athens, GA, USA; GlaxoSmithKline Research & Development Ltd., Addenbrooke’s Hospital, Cambridge, UK. J Brown GlaxoSmithKline Research & Development Ltd., Addenbrooke’s Hospital, Cambridge, UK.