Examining the Processability Theory
The Case of Adjective Agreement in L2 Swedish
The Processability Theory (PT), originating from the German ZISA Project and recently revised by Pienemann (1993, in prep.), claims that the order of grammatical development in a second language is determined by a hierarchy of psycholinguistic constraints on the processability of grammatical structures. The present paper discusses some problematic aspects of this theory and argues for a dynamic view of L2 acquisition in which factors which drive acquisition ahead are also taken into account. It is suggested that a Principle of Perceived Communicative Value (PCV) plays a part in conditioning the order of L2 development. The relative role of processability and communicative value factors is investigated here in a case where they compete.
The acquisition of adjective agreement in L2 Swedish is chosen as a test case to examine predictions about the order of development derived from PT and PCV. This permits the comparison of a phrasal (NP) and inter-phrasal (subject-predicative) syntactic domain as well as the comparison of different morphological categories (gender and number). Longitudinal data are gathered from a corpus of conversations with six adult learners reflecting successive stages of development for each individual from the beginning stage to an advanced level.
The results indicate that the nature of the morphological category is decisive in determining acquisition order, which means that PCV is effective and overrules PT in those cases where the two are in conflict. On the other hand, if the same morpho-logical category is compared in different syntactic domains, PTs prediction that phrasal agreement comes before inter-phrasal agreement is borne out. This suggests that the two principles of processability and communicative relevance interact, and that a theory of processability is neither sufficient nor invalid, but needs to be placed in the context of a wider model of L2 development. It lends support to the dynamic view of L2 acquisition discussed in the paper.