Phonetically Driven Phonology: The Role of OT and Inductive Grounding

Functionalist phonetic literature has shown how the phonologies of human languages are arranged to facilitate ease of articulation and perception. The explanatory force of phonological theory is greatly increased if it can directly access these research results. There are two formal mechanisms that together can facilitate the link-up of formal to functional work. As others have noted, Optimality Theory, with its emphasis on directly incorporating principles of markedness, can serve as part of the bridge. Another mechanism is proposed here: an algorithm for inductive grounding permits the language learner to access the knowledge gained from experience in articulation and perception, and form from it the appropriate set of formal phonological constraints. 1 I would like to thank Marco Baroni, Patricia Keating, Donca Steriade, and members of talk audiences at MIT, Arizona, Tilburg, Utrecht, Cornell, UC Santa Cruz, UCLA, and the Formalism/Functionalism conference for helpful input in the preparation of this paper. Hayes: Phonetically-Driven Phonology p. 2 1. Phonological Functionalism The difference between formalist and functionalist approaches in linguistics has taken different forms in different subfields. For phonology, and particularly for the study of fully-productive sound patterns, the functionalist approach has traditionally been phonetic in character. For some time, work in the phonetic literature, such as Ohala (1974, 1978, 1981, 1983), Ohala and Ohala (1993), Liljencrants and Lindblom (1972), Lindblom (1983), and Westbury and Keating (1986), has argued that the sound patterns of languages are effectively arranged to facilitate ease of articulation and distinctness of contrasting forms in perception. In this view, much of the patterning of phonology reflects principles of good design. In contemporary phonological theorizing, such a view has not been widely adopted. Phonology has been modeled as a formal system, set up to mirror the characteristic phonological behavior of languages. Occasionally, scholars have made a nod towards the phonetic sensibleness of a particular proposal. But on the whole, the divide between formal and functionalist approaches in phonology has been as deep as anywhere else in the study of language. It would be pointless (albeit fun) to discuss reasons for this based on the sociology of the fields of phonetics and phonology. More pertinently, I will claim that part of the problem has been that phonological theory has not until recently advanced to the point where a serious coming to grips with phonetic functionalism would be workable. 2. Optimality Theory The novel approach to linguistic theorizing known as Optimality Theory (Prince and Smolensky 1993) appears to offer the prospect of a major change in this situation. Here are some of the basic premises of the theory as I construe it. First, phonological grammar is not arranged in the manner of Chomsky and Halle (1968), in essence as an assembly line converting underlying to surface representations in a series of steps. Instead, the phonology selects an output form from the set of logical possibilities. It makes its selection using a large set of constraints, which specify what is “good” about an output, in the following two ways: (1) a. Phonotactics: “The output should have phonological property X.” b. Faithfulness: “The output should resemble the input for property Y.” Phonotactic constraints express properties of phonological markedness, which are typically uncontroversial. For example, they require that syllables be open, or that front vowels be unrounded, and so on. The Faithfulness constraints embody a detailed factorization of what it means for the output to resemble the input; they are fully satisfied when the output is identical to the input. Hayes: Phonetically-Driven Phonology p. 3 Constraints can conflict with each other. Often, it is impossible for the output to have the desired phonotactic properties and also be faithful to the input; or for two different phonotactic constraints to be satisfied simultaneously. Therefore, all constraints are prioritized; that is, ranked. Prioritization drives a specific winnowing process (not described here) that ultimately selects the output of the grammar from the set of logical possibilities by ruling out all but a single winner. I will take the general line that Optimality Theory is a good thing. First, it shares the virtues of other formal theories: when well implemented, such theories provide falsifiability, so that the errors in an analysis can lead to improvement or replacement. Further, formal theories characteristically increase the pattern recognition capacity of the analyst. For example, it was only when the formal theory of moras was introduced (Hyman 1985) that it became clear that compensatory phonological processes always conserve mora count (see Hyman, and for elaboration Hayes 1989). Second, Optimality Theory has permitted solutions to problems that simply were not treatable in earlier theories. Examples are the metrical phonology of Guugu Yimidhirr (Kager, to appear), or the long-standing ordering paradoxes involving phonology and reduplication (McCarthy and Prince 1995). Most crucially, Optimality Theory has the advantage of allowing us to incorporate general principles of markedness into language-specific analyses. Previously, a formal phonology consisted of a set of somewhat arbitrary-looking rules. The analyst could only look at the rules “from the outside” and determine how they reflect general principles of markedness (or at best, supplement the rules with additional markedness principles, as in Chomsky and Halle (1968, Ch. 9), Schachter (1969), or Chen (1973)). Under Optimality Theory, the principles of markedness (stated explicitly and ranked) form the sole ingredients of the language-specific analysis. The mechanism of selection by ranked constraints turns out to be such an amazingly powerful device that it can do all the rest. Since rankings are the only arbitrary element in the system, the principled character of language-specific analyses is greatly increased. This is necessarily an argument by assertion, but I believe a fair comparison of the many phonological analyses of the same material in both frameworks would support it. 2 For the original presentation of Optimality Theory, the reader is referred to Prince and Smolensky (1993) or to McCarthy and Prince (1994) for a recent summary. 3 Here are two other examples. (a) The formal theory of intonational representation developed by Pierrehumbert (1980) led her to discover English intonational contours not previously noticed. (b) The theory of prosodic domains of Selkirk (1980) led Hayes and Lahiri (1991) to find close links between intonation and segmental phonology in Bengali that would not have otherwise been observed. 4 Much of the Optimality Theory analytical literature is currently posted on the World Wide Web at http://ruccs.rutgers.edu/roa.html, and may be downloaded. Hayes: Phonetically-Driven Phonology p. 4 3. What is a Principled Constraint? The question of what makes a constraint “principled” is one that may be debated. The currently most popular answer, I think, relies on typological evidence: a principled constraint is one that “does work” in many languages, and does it in different ways. But there is another answer to the question of what makes a constraint principled: a constraint can be justified on functional grounds. In the case of phonetic functionalism, a well-motivated phonological constraint would be one that either renders speech easier to articulate or renders contrasting forms easier to distinguish perceptually. From the functionalist point of view, such constraints are a priori plausible, under the reasonable hypothesis that language is a biological system that is designed to perform its job well and efficiently. Optimality Theory thus presents a new and important opportunity to phonological theorists. Given that the theory thrives on principled constraints, and given that functionally motivated phonetic constraints are inherently principled, the clear route to take is to explore how much of phonology can be constructed on this basis. One might call such an approach “Phonetically-Driven Optimality-theoretic Phonology.” A theory of this kind would help close the long-standing and regrettable gap between phonology and phonetics. 4. Sample Result: Segment Licensing The position just taken regarding phonetics and Optimality Theory is not original with me, but is inspired by ongoing research of Steriade (1993, 1995b, in progress), as well as work such as Archangeli and Pulleyblank (1994), Jun (1995a,b), Flemming (1995), Kaun (1995a,b), Silverman (1995), Myers (1996), Gordon (forthcoming), and Kirchner (in progress). Although I obviously cannot review all of this work, I will mention one particularly vivid example. Steriade (1995b, in progress) considers the very basic question of segmental phonotactics in phonology: what segments are allowed to occur where? Her perspective is a novel one, taking the line that perception is the dominant factor. Roughly speaking, Steriade suggests that segments preferentially occur where they can best be heard. The crucial part is that many segments (for example, voiceless stops) are rendered audible largely or entirely by the contextual acoustic cues that they engender on neighboring segments through coarticulation. In such a situation, it is clearly to the advantage of particular languages to place strong restrictions on the phonological locations of such segments. Following this approach, and incorporating a number of results from research in speech perception, Steriade is able to reconstruct the traditional typology of “segment licensing,” including what was previously imagined to be an across-the-board preference for consonants to occur in syllable onset position. She goes on to show that there in fact Hayes: Phonetically-Driven Phonology p. 5 are areas where this putative preference fails as an account of segmental phonotactics: one example is the preference for retroflexes to occur postvocalically (in either onset or coda); preglottalized sonorants work similarly. As Steriade shows, these otherwisebaffling cases have specific explanations, based on the peculiar acoustics of the segments involved. She then makes use of Optimality Theory to develop explicit formal analyses of the relevant cases.