A Note on Processability Theory and Developmental Sequences of Second Language Acquisition

Acquisition sequence (or order) is one of the core issues in language acquisition research. The present paper discusses second language research on developmental sequences, focusing on a psycholinguistically based theory—Processability Theory. Based on a number of L1 speech production models and Lexical-Functional Grammar, Processability Theory describes, explains and predicts how a learner's ability to process new linguistic rules develops. From a language processing perspective, L2 acquisition is considered as a cumulative and sequential developmental process that involves the activation of information exchange procedures. The activation of implicationally ordered processing procedures drives L2 grammar learning through a hierarchy of acquisition stages. The stages of acquisition provide specific information on what L2 learners are able and unable to learn at different points in time. This understanding enables us to focus on the learner's level of ability and to optimize L2 pedagogy including teaching approaches, textbook design and language assessment.