From telegraphic to natural language: an expansion system in a pictogrambased AAC application

Esta tesis doctoral presenta un sistema de compansion que transforma el lenguaje telegrafico (frases formadas por palabras de contenido no flexionadas), derivado de la comunicacion aumentativa y alternativa (CAA) basada en pictogramas, a lenguaje natural en catalan y en castellano. El sistema ha sido disenado para mejorar la comunicacion de personas usuarias de CAA que habitualmente tienen graves problemas en el habla, asi como problemas motrices, y que utilizan metodos de comunicacion basados en pictogramas en su vida diaria. El sistema de compansion tiene dos componentes principales: un analizador de dependencias sintactico-semantico y un generador que construye la frase final. Este sistema se ha evaluado mediante pruebas tecnicas y los resultados muestran que el 99,66% de las frases generadas, dentro de una gramatica restringida, fueron consideradas correctas por tres anotadores independientes. Paralelamente, tambien se ha investigado e implementado una interfaz de usuario con un sistema de prediccion de pictogramas para poder probar el sistema de compansion con usuarios finales. El sistema en conjunto se ha probado con cuatro participantes con paralisis cerebral severa y diferentes grados de competencia linguistica y de discapacidad intelectual. Durante los tests, los participantes adquirieron nuevas capacidades linguisticas mientras utilizaban el sistema de compansion que se mostro como una fuente de motivacion. El sistema se adapto a las competencias linguisticas de cada uno y no requirio ninguna curva de aprendizaje cuando no se utilizo ninguna de sus caracteristicas especiales. Finalmente, los resultados cualitativos y cuantitativos muestran un incremento medio de la ratio de comunicacion del 41,59% si se compara con el mismo dispositivo de comunicacion sin el sistema de compansion y una mejora global en la experiencia comunicativa cuando el resultado final es en lenguaje natural. --- This doctoral dissertation presents a compansion system that transforms the telegraphic language (utterances with only uninflected content words) that comes from the use of pictogram-based Augmentative and Alternative Communication (AAC) into natural language in Catalan and Spanish. The system has been designed to improve the communication of people who rely on AAC, who usually have severe speech or motor impairments and use pictogram-based communication methods in their daily life. The compansion system has two main components: a syntactic-semantic dependency parser and a generator that constructs the final sentence. The system has been technically evaluated and results show that 99,66% of the sentences generated by it, taking into account the restrictions of a constrained grammar, were considered correct by three independent annotators. Furthermore, a user interface with a pictogram prediction system has also been researched and implemented during the thesis in order to test it with end-users. The system as a whole was tested with 4 participants with severe cerebral palsy and ranging degrees of linguistic competence and intellectual disabilities. During tests, participants were able to learn new linguistic skills while using the compansion system, which proved a source of motivation. The system can also be adapted to the linguistic competence of each person and required no learning curve during tests when none of its special features were used. Finally, qualitative and quantitative results showed a mean communication rate increase of 41,59%, compared to the same communication device without the compansion system, and an overall improvement in the communication experience when the output is in natural language.