Quatrain form in English folk verse

Quatrains in English folk verse are governed by laws that regulate the patterns of truncation (nonfilling of metrical positions) at the ends of lines. Each truncation pattern (we claim 26) is adhered to consistently through multiple stanzas and defines a verse type. Our descriptive goal is to account for why these and only these truncation patterns exist. Our crucial hypothesis is that the function of truncated lines is to render SALIENT certain layers in the natural constituency of the quatrain: the line, the couplet, or the quatrain as a whole. All three cannot be rendered salient at once, so the saliency constraints conflict. Each saliency constraint also conflicts with metrical constraints, which require that metrical positions be filled with appropriate syllables and stresses. The twenty-six well-formed quatrain types each represent a particular prioritization of the conflicting constraints. We formalize this in optimality theory (Prince & Smolensky 1993): the inventory of types is derived as the factorial typology of our constraint set; namely, the set of outputs of all grammars obtained by freely ranking the violable constraints. We also account for differing text frequencies in our data corpus by assigning each constraint a range of possible strengths, and from this develop an optimality-theoretic account of gradient well-formedness judgments.*