Statistical analysis of textual data from corpora of written communication - New results from an italian interdisciplinary research program (EASIEST)

The Project "EASIEST: Espressione Autistica. Studio Interdisciplinare con Elaborazione Statistico-Testuale" [EASIEST: Autistic Expression. An Interdisciplinar Study based on Statistical and Textual Analysis] is an Italian interdisciplinary research program involving linguistics, neuropsychiatry, psychology, sociology and statistics (especially text mining, content analysis and computer-aided analysis of textual data) aimed at studying the linguistic features of texts written by individuals with autism (in this case 38 persons who use facilitated communication) and facilitators (without disabilities). In the frame of this Project, the research group collected large corpora of texts written during session of facilitated communication (FC) in four accredited FC centers in Italy . The results support the existence of lexis and distributional patterns of grammatical categories that are characteristic of the written production of individuals with autism and that are different from those of facilitators. The lemmas used by individuals with autism were quantitatively and qualitatively different from those used by facilitators. The lexis of individuals with autism overlapped only partially with that of facilitators. Measures of lexical richness showed a greater number of different words and higher lexical richness in the group including individuals with autism as compared to the group of facilitators. From a qualitative viewpoint, lexical richness also resulted from both the use of words not attributable to the common lexis of Italian in both ordinary and unusual contexts and the emergence of a certain amount of original hapaxes (words with frequency equal to one). High register words, that do not belong to the Italian basic vocabulary, were also used by children under 10 years of age. Stylized language also emerges from creative expressions and the creation of neologisms, coined according to the word-formation rules of the Italian language. The distinctive linguistic features identified by the statistical analysis of lexical data and analyzed in depth by means of traditional qualitative methods derive from the greater complexity of texts written by individuals with autism in terms of both lexis and morpho-syntactic structures. In texts written by individuals with autism, grammatical categories (nouns, adjectives, verbs, adverbs etc.) show a specific distribution and particular syntactic structures tend to emerge. For example, individuals with autism tend to resort more frequently to modifiers as compared to facilitators: adverbs and adjectives. Moreover, they tend to omit grammatical words (prepositions, conjunctions, articles, pronouns) when this does not hamper the understanding of the sentence meaning. The texts written by individuals with autism were similar to each other and differed from the texts produced by their facilitators which, in their turn, resembled each other. The findings of this first research project supported the hypothesis that texts written by individuals with autism were characterized by distinctive and consistent lexical features. Compared with other studies highlighting lexical poverty and morpho-sintactical impairment, the results of the EASIEST project point to unexpected communicative skills in individuals with autism. Moreover, the conjoint linguistic and statistical methods adopted in this study appeared effective in highlighting differences among the groups and would be suitable for an interdisciplinary approach to the study of language in autism.