The Interface Hypothesis as a framework for studying L1 attrition

This chapter focuses on first generation individual attrition from the point of view of the Interface Hypothesis (IH), which proposes that structures at the interface between syntax and other cognitive domains, such as pragmatics, are more likely to undergo attrition than structures that do not involve such an interface, and discusses recent research that provides evidence of the selectivity and reversibility of individual first language (L1) attrition. This research provides supporting evidence for the IH as it reveals that attrition affects structures at the syntax-pragmatics interface but not structures requiring the satisfaction of semantic conditions. This chapter also reviews research that supports Sorace’s (2011, 2016) proposal that individual L1 attrition affects only the ability to process interface structures but not knowledge representations, as it reveals that attrition only affects online sensitivity with structures at the syntax-pragmatics interface rather than causing a permanent change in speakers’ L1 knowledge representations.