Constraining Morphological Variation and Development: Agreement in L2 Spanish

Structure building in language acquisition involves the adding of successive nodes in a hierarchical structure; its application is seen in the realm of syntax for both L1 (e.g. Clahsen, Penke & Parodi, 1993; Vainikka, 1993) and L2 acquisition (e.g. Vainikka & Young-Scholten, 1994, 1996), and to some extent within phonology as well (Brown, 1997). Although researchers in morphological theory argue that hierarchical structure should be built into the organization of morphological features (e.g. Harley & Ritter 2002; Cowper 2005), the application of structure building in the domain of morphology has received minimal attention within L1/L2 acquisition. The purpose of this paper is to explore to what extent feature geometric models of morphology may be applicable to the domain of L2 agreement: do L2 learners acquire structure gradually in the domain of morphology? Within a generative framework, morphological development has been tied to syntactic development (Vainikka & Young-Scholten 1994, 1996). The successful usage of person and number agreement was taken as a diagnostic for the acquisition of phrases such as AgrP (Agreement Phrase), and the successful usage of past tense morphology as a diagnostic for the acquisition of the TP (Tense Phrase). Compare (1), which the authors analyze as an unraised infinitive in a bare-VP tree, with (2), which shows both agreement and raising to a higher syntactic projection.