Against strict stratum-internal transparency: within-stratum countershifting in Gallipoli Serbian

This paper challenges the universality of the stratum-internal transparency principle of Stratal Optimality Theory. According to this principle, processes that apply within the same phonological stratum can only interact transparently, with opacity emerging solely as an epiphenomenon of phonology-morphosyntax interleaving. I present a previously unexamined case of countershifting opacity in Gallipoli Serbian. In this dialect of Bosnian/Croatian/Montenegrin/Serbian, stress falls on the word’s only High-toned syllable—unless the High-toned syllable is light and final, in which case stress falls on the penult. Crucially, final vowel shortening opacifies this generalization: final light syllables that derive from original heavies by final shortening bear stress on the surface, rendering the ban on stressed final lights non-surface-true. These opaquely interacting processes demonstrably apply in the same phonological stratum. Moreover, even with additional, language-specific stratal domains, isolating all opaquely interacting processes into separate strata remains impossible. This study thus provides empirical evidence for within-stratum opacity, even under more permissive versions of Stratal Optimality Theory.