SLI in Children: Movement, Economy, and Deficits in the Computational-Syntactic System

Abstract

The linguistic characteristics of a boy (AZ) with specific language impairment (SLI) are presented. AZ illustrates the linguistic characteristics of Grammatical SLI. Morphosyntactic investigations reveal that all inflectional forms are present but are not used consistently. The impairment extends to syntactically complex utterances involving embedded structures at phrase and clause level and to arguments and wh-movement. There is true optionality in AZ's grammar. I propose that optional movement characterizes Grammatical SLI. Based on the Representation Deficit for Dependent Relationships account, I claim that the underlying deficit causing optional movement is in the syntactic computational system. A deficit in the operation, Move F, was not supported. A deficit with Economy (R. Manzini, personal communication, January 1998) was considered. I argue that Last Resort may be viewed as comprising two principles: Economy 1 ensures that the operation Move F is only permitted if it satisfies an appropriate feature-checking relation; Economy 2 forces movement of unchecked features. Hence, movement is obligatory. The data do not support a deficit with Economy 1. I propose that Economy 2 is missing in SLI grammar and this deficit causes optional movement. I provide an explanation of how the proposed characterization and underlying deficit can account for the range of syntactic findings for children with Grammatical SLI.