Twin speak : a case study of language development in a set of fraternal twins where one has Down syndrome

Abstract

This thesis discusses the language development of a set of fifteen month old male fraternal twins, where one is affected with Down syndrome. The focus of the discussion is the twins' gradual development from verbal and non-verbal prelinguistic communication to the onset of first words. The present researcher filmed her young subjects a number of times over a period of four months, allowing her to obtain data of a cross-sectional nature for analysis. The analysis attempts to identify the various characteristics which make this case so particular and to discuss the effect of such characteristics on the subjects' language acquisition. The discussion therefore investigates the influence of twinship on the infants' individual development as well as the influence that Down syndrome has on one, or possibly both, of the twins. This study analyses the data collected through filming with reference to the theories and writings of psycholinguists such as Lust (2006), Berko Gleason (2009), Foster (1990), Beveridge & Conti-Ramsden (1987), Mogford (1997), Ingram (1990) and Rondal (2003). This case study provides observational insight into the infants' language acquisition in their exceptional circumstance. The study is therefore of a qualitative nature and is not representative of all twins or of all individuals with Down syndrome.