UC Santa Cruz

There has been a recurrent debate in generative phonology concerning the inclusion of hierarchical prosodic structure in phonological representations. On one side, there are those who argue that prosodic structure plays an indispensable role in the conditioning of phonological phenomena, especially stress, intonation, and segmental phonotactics. On the other side of the divide are researchers who suggest that all such phenomena yield to empirically adequate non-structural analyses, which are independently favored by criteria of theoretical parsimony.

This dissertation focuses on one aspect of the larger debate over prosodic organization: the existence of the metrical foot. In standard conceptions of phonological structure the foot is a prosodic constituent, falling between the syllable and the word, which mediates the assignment of word-level stress. The foot obviously has no role to play in non-structural theories of prosody. Such frameworks assume that stress assignment is not dependent on prosodic constituents, but is instead directly computed over segments or syllables on a metrical grid.

The evidence brought to bear on the choice of prosodic theory has, by-and-large, been drawn from the typology of attested stress patterns. Both structural and non-structural theories of stress appear capable of modelling roughly the same range of stress systems. Consequently, many of the arguments for or against foot structure have centered on the ability of each theory to express the typology of stress assignment in a compact, elegant, and predictive way. This dissertation expands the terms of the debate by examining foot-conditioned phonotactics, and to a lesser extent foot-conditioned morphology, as a window on the nature of prosodic constituency in natural language.

A major conclusion of this dissertation is that hierarchical prosodic structure must be admitted as part of phonological representations in order to capture the full range of prosodically-conditioned segmental phonotactics found in natural language. Three case studies form the heart of this claim. Specifically, I show that Huariapano, Uspanteko, and Irish all manifest foot-dependent phonotactics that cannot be insightfully analyzed without recourse to abstract metrical structure. Importantly, these arguments go beyond claims about relative theoretical elegance: non-structural analyses simply fail to account for the relevant phonological phenomena in an explanatory way.

In arguing for a foot-based theory of stress assignment, I also make the case for a fairly traditional conception of the metrical foot. First, I contend that stress is always assigned on the basis of foot structure, and only to foot heads, though feet may be unstressed or `covert' as well. Second, I argue that feet are always maximally binary, even in languages where stress assignment itself is ambiguous between binary and unbounded footing. Third, I propose that any given language makes use of at most one system or `tier' of metrical organization (the uniformity of footing hypothesis). In particular, I demonstrate that the rhythmic phonology of Huariapano can and should be modeled within a single, unified system of foot structure, despite previous claims to the contrary. Along the way, I identify a novel source of phonological prominence effects: the augmentation of foot-initial syllables.

The dissertation closes with an artificial grammar study exploring how language learners acquire foot-conditioned segmental phonotactics. Given the `hidden' character of abstract prosodic structure, foot-conditioned phonotactics pose an interesting learning problem. This is especially true given the recent rise of the view that all synchronic phonological knowledge is the result of inductive learning over phonetic regularities in the speech stream. The results of the artificial grammar study suggest that speakers of both English and Japanese were inclined to learn a stress-conditioned vowel phonotactic in terms of foot structure rather than stress per se. The experiment thus supports the claim that language learning is sensitive to a foot-based parsing bias that encourages the use of the foot as a general explanatory device in acquisition. These findings provide a possible explanation for why binary foot structure is found in languages lacking rhythmic, foot-based stress, and suggest that the foot may be a prosodic universal.