Against an L2 morphological deficit as an explanation for the differences between native and non-native grammars

One proposed explanation for the observed differences between native and non-native speakers has been that certain peripheral systems interacting with the computational system are defective in L2 acquisition. This paper will consider some of the predictions that follow from assuming that the morphological module which interacts with the computational system (or their interface) is defective. If this basic assumption is correct, we should expect all learners to be able to acquire the L2 grammar equally well, and where mistakes are found they should be due to problems in the morphology. The results of an empirical study of the acquisition of grammatical gender in advanced English and Italian speakers of L2 Spanish do not support these predictions, as the errors found appear to be syntactic in nature.