Covert Representations, Contrast, and the Acquisition of Lexical Accent
Lexical accent presents in a particularly sharp form some basic problems that learning models must overcome. Dresher Kaye (1990) attempt to address these problems in the context of a learning model for a parametric metrical phonology for languages with predictable stress systems. I will show how this model, as modified by Dresher (1994) can be extended to learn stress systems that incorporate lexical accent, at least in the case of a constructed simple language inspired by Russian. Many of the problems in acquiring lexical accent have to do with hidden structure. Hidden structure has been discussed in the context of 'overt' and 'covert' structures. I argue that these categories are fluid, and not fixed, as might sometimes appear from other learning models. Though I assume a derivational parametric metrical theory, the basic strategies have some affinity with ideas proposed by Tesar and his colleagues (Tesar et al. 2003; Tesar 2006; 2014) for learning an Optimality Theoretic grammar. The notion of contrast plays an important role in the acquisition of lexical representations, as suggested by Tesar (2006; 2014) I will extend the approach of Dresher (2009) which considers contrast in the context of segmental features, to lexical accent. Recognizing the role of establishing contrasts in the lexical inventory will also help to streamline the system of cues proposed by Dresher Kaye (1990) In particular, I show how the learning model in Dresher and Kaye (1990) as modified by Dresher (1994) can be revised and extended to learn the lexical accent system of a constructed simple language inspired by Russian. Importantly, this model compares multiple forms in order to establish contrasts in the lexicon. While the model is sufficiently specified to understand how it works on the simple constructed example, it remains to be implemented computationally. The plan of this chapter is as follows. In Section 8.2, I briefly review what the grammar of stress and metrical representations look like in the Simplified Bracketed Grid theory. Problems attending to the acquisition of metrical representations and the grammar of stress are reviewed in Section 8.3, where I present the learning model of Dresher Kaye (1990) Section 8.4 takes up stress systems characterized by lexical accent. In Section 8.4.1 I briefly review the PAKA world model of Tesar and his associates, and in Section 8.4.2 I outline a learning model for lexical accent that builds upon the proposals of Dresher Kaye (1990) and Dresher (1994) The role of contrast in the acquisition of segmental and metrical representations is discussed in Section 8.5. Section 8.6 is a brief conclusion.