Investigating the Development of a Developmental Disorder: Mapping the Trajectory of Lexical Development in Specific Language Impairment
Cristina McKean
Location: CURDS Seminar Room, 4th Floor, Claremont Bridge
Time/Date: 26th November 2009, 12:00 - 13:00
Abstract
There is increasing consensus that to understand developmental disorders we must apply developmental theoretical models and methodologies. To develop a fully specified developmental model of a developmental disorder we must understand both the nature of the innate causal processing deficits of the disorder and also how these deficits then change the developmental process. This study aimed to examine the second of these issues with respect to Specific Language Impairment (SLI) and so describe the altered trajectory of development in this group of children.
Very little empirical research exists which maps the altered trajectory of SLI. This study sought to contribute to that necessary empirical data and also to consider whether the application of a developmental methodology and perspective adds to our understanding.
The data presented focuses on the development of the lexicon in SLI. Lexical and phonological processing and their interaction with phonological working memory capacity are thought to be crucial to the ontogeny of SLI. Tasks were developed to create a window into the nature of the developing lexicon. A series of longitudinal case studies of children with SLI were completed and cross sectional data collected from a group of typically developing (TD) children.
In TD children the trajectories of development were suggestive of increasing abstraction of sub-lexical/phonological knowledge and of functional reorganisation in the developing lexicon and the speech processing mechanism. The developmental trajectories of the children with SLI suggest that this group of children may develop a different lexical processing architecture from typically developing children which does not reach the levels of efficiency of TD children’s speech processing mechanisms. There is tentative support for the existence of a deficit in schema abstraction across the lexicon and an absence of functional reorganisation. The possibility that these results represent entrenchment within a self-organising network, and the possible relationship to issues of timing and critical periods is discussed and the broader implications of developmental emergent conceptualisations of language impairment for research methodologies, diagnosis and therapy considered.
|
Dr Cristina McKean
|
|
Published: 13th October 2009