© Science and Education Publishing DOI:10.12691/ajap-2-4-2 The “Critical Mass Hypothesis”: Morphosynatx Development among Typically Developing Child and a Child with Developmental Language Disorder

Abstract Mass Critical Hypothesis is a new concept in the study of child language and/or developmental language disorder. The hypothesis states that the morphosyntax of children can develop only if they have acquired (or can produce) a certain amount of different words. The goal of the present research was to test the generalizability and reliability of the hypothesis. For this, one typically developing child and one child with developmental language disorder from Child Language Data Exchange System/CHILDES (MacWhinney, 2000) were taken. The CHAT file was non-elicited and non-directed spontaneous speech. Computerized Language Analysis (CLAN) v.30 for Windows was employed to analyze the non-elicited spontaneous speech of the typically developing child and the child with developmental language disorder. For both cases, Mean Length of Utterance (MLU) and Pearson product moment correlation coefficient (r) were calculated. Based on observed range of number of types of morpheme produced, the present study supports the notion of ‘Mass Critical Hypothesis ’ existence in both typically developing child and the child with developmental language disorder