The Influence of Morphosyntactic Network Complexity on Typical and Atypical Language Learning

Project Summary The proposed project details an innovative line of research that draws on advanced tools from the field of network science to elucidate typical and atypical language learning mechanisms in adults. Network analysis of natural language has revealed a number of global structural patterns emerging from relationships (used to construct network edges) between words (used as network nodes). Informed by the naturally-occurring network architecture of real-world languages, we will construct miniature artificial languages that display emergent properties of existing language systems and measure the extent to which these languages are learned by adults with typical development (TD) and those with developmental language disorder (DLD) (Aim 1). Given that DLD is often associated with deficits in processing and producing complex morphosyntax, we will concentrate on networks in which edges between words represent either their co-occurrence in a sentence or overlap in morphological family (e.g., eater, eating). In Aim 2, we will examine whether language learning deficits in adults with DLD might be recast as a hyperfocus on local-level information (i.e., “oddball” structures or individual word frequency) at the expense of the broader architecture of the language learning environment. To strengthen links between deficits in language learning and expressive language, Aim 3 calls for the network analysis of elicited speech samples to reveal whether individuals less sensitive to complexity in learning might also display reduced complexity in their language output. Of individuals diagnosed with receptive and expressive language disorder in childhood, the vast majority continue to struggle with language impairment in adulthood. Despite a pressing need for expansion of adult-oriented language interventions, characterization of the full scope of deficits in individuals with DLD, in addition to their language learning mechanisms beyond childhood, is an understudied area.