Upstepping vowel height

The main goal of this paper is to argue for a unified analysis of two stepwise vowel raising processes known as metaphony, those of Proto-Spanish and Lena Asturian, within the framework of Optimality Theory (OT). It is shown that previous serial accounts based on autosegmental spreading rules operating on vowel height features are unable to capture adquately the unitary nature of the metaphony shifts. Our OT approach stepwise vowel raising in both Proto-Spanish and Lena Asturian arises primarily in the interaction of two constraints, unranked with respect to each other. First, a markedness constraint which demands that the stressed vowel agree in vowel-height features with a following high vocoid within a word’s dominant foot; and second, a local conjunction of identity constraints on contrastive vowel height features which enforces stepwise raising by effectively restricting unfaithfulness between input and output to at most one feature. Both the agreement and the constraint conjunction constraint dominate the individual faithfulness constraints requiring input-output identity of vowel height features. Finally, it is shown that this analysis can be easily extended to handle the somewwhat different metaphonic shifts in Nalón Valley Asturian, closely related to the Lena variety, by appealing to a different ranking of the same constraints proposed for the Lena variety, a desirable result predicted by factorial typology.