Clinical Psychology Applications ofAutomated Syntax AnalysisTova [email protected]: Dr. Mitch MarcusApril 18, 2008AbstractIn this research we analyze the contribution of automatic syntax analysis to the fieldof clinical psychology. Using data from a cognitive study on patients with dementia,sentence grammar structures are extracted from transcribed speech samples and areanalyzed for patterns of speech complexity. These are used to explore correlations be-tween cognitive impairment due to differing diagnoses of dementia and speech syntax.The hypothesis is that patients suffering from dementia affecting executive functioningwill show significantly less use of syntactic phenomena which require a high level of log-ical organization. The method chosen is to employ tools that identify specific sentencestructures and their rates of occurrence, and use these results to identify significant dif-ferences between the group with dementia and the control group. The results supportthis hypothesis, finding significant differences for certain syntactic patterns.1 IntroductionSyntax analysis, a field within computational linguistics, is used to identify features of speechthat can provide information about the author and tone of a textual segment. To accomplishthis, sophisticated tactics are required, including analysis of content word choice, sentencesas a whole and within-sentence word relationships.This kind of analysis has many applications. One example is using syntax to determinesentiment in written text. Popular web sites such as Amazon.com and Yahoo! allow users towrite reviews about products that appear on their site. A sentiment analysis tool could createa simple and concise way to view these free-form pieces of text, by automatically labelingthem as positive or negative reviews (Pang, Lee and Vaithyanathan, 2002). Thus, automatedsyntax analysis can be used to streamline online textual information, an increasing concernwith the continual growth of digitally available data.1The research presented here is intended to employ syntax analysis tools to approach aproblem within clinical psychology, by developing a model to identify correlations of linguisticdeficits in a particular manifestation of frontotemporal dementia, which has previously beendefined primarily by social and organizational difficulties. Some forms of dementia includedisorganized sp eech as a symptom, however in these cases the speech patters are easilyrecognizable by a doctor during a conversation with the patient. We propose here thatalthough they are not easily discernible, syntax may be affected by FTD, but stronger toolsare required to notice them, and simply listening to a patient is not enough.In this research we focus on frontotemporal dementia, however further applications ofthese methods can be used for research problems in many different areas.2 Related Work2.1 Text CategorizationPrevious work in textual analysis has focused on categorizations of large amounts of textualdata into preset categories. One application is determining the author or genre of a piece oftext. Classification by overall sentiment, positive or negative valence, is another example.Research by Pang et al focused on categorization of online movie reviews, into one of twodistinct groups: positive or negative reviews, using a number of different artificial intelligencemethods. The task was found to be significantly harder than that of topic classification. Theperformance of a machine learning classifier still achieved high accuracy results, than usingrules that humans thought to be important in this type of classification (prompting thequestion of reliance on prior intuitions).One of the difficulties arises from the source of the data. These short reviews often usea complex stylistic structure to indicate an overall opinion of a product or movie, such aspointing out the positive elements of the product before declaring that it really is a terribleinvestment. Since the methods currently used analyze each sentence as a separate unit, it isdifficult to extract on overarching opinion.2.2 Countertranference and languageDahl and Teller (1978) raised the idea that one could extract syntactic cues from speechduring psychoanalysis sessions, and use these to gain insight into the therapist’s underlyingmental state during the session. This mental state is part of a Freudian phenomenon calledcountertransference, which is an important aspect of therapy in Freudian analysis.In their research, Dahl and Teller used hand annotated, transcribed session between aspecific patient and his analyst. Since hand annotation is difficult and time consuming, weavoided this method for our data set and focused on automated tools for speech tagging andparsing. This allows for flexibility in the amount of data and the speed of analysis.22.3 Cognitive Impairment and LanguageExperimental studies involving an oral task to establish cognitive abilities are often the focusof cognitive psychology research. These studies involve a significant amount of speech data,and are likely to benefit from techniques similar to those presented here. Automatic syntaxanalysis can produce a consistent and objective measure of features of speech output. Thisenables the experimenters to create a linguistic profile of the subjects, and observe patternsand trends that can help in diagnosis and in defining a disorders properties, while side-stepping such issues as between-experimenter discrepancies and observer biases.A study was conducted which measured syntactic complexity of transcribed speech, wherepatients with mild cognitive dementia were asked to retell a story from memory (Roark,Mitchell and Hollingshead, 2007). This study was different from previous studies in thatautomatic parsers were used to parse transcribed spoken samples, rather than requiring ahuman eye. The hypothesis was that subjects with Mild Cognitive Impairment (MCI) wouldshow less grammatically complex speech than healthy subjects, using objective methods toevaluate sentence complexity. Two different measures of syntactic complexity, each a productof parser derivation, were used for evaluation. The hypothesis was that those with MCIwould show lower syntactic complexity, thus enabling syntactic complexity to be considereda diagnostic criterion.The Charniak parser (Charniak, 2000) showed a high correlation between findings usingautomatic parsing and those using manual parsing. However, the results of the study