Morpheme-specific Exceptional Processes and Emergent Unmarkedness in Vowel Harmony

In this paper I discuss exceptional occurrences in the nominal and verbal morphology of Assamese and the role of indexed markedness constraints in accounting for these exceptions. Assamese vowel harmony is a 'directional' right-to-left regressive harmony system, which normally ignores morphological boundaries. In contrast to the general process of harmony, this work shows that some morphemes can influence vowel harmony and result in exceptional patterns. Following Pater (2006) it is shown that indexation of markedness constraints can account for these exceptional occurrences. This work also shows that the caveat in Pater (2006) about such constraints' ability to subvert the universal constraint ranking ROOT FAITH >> AFFIX FAITH is indeed borne true. Consequently, the Assamese examples show that indexed constraints lead to an exceptional alternation where [±Back] harmony occurs only in the root and the suffixal [±Back] values remain unaltered. I argue that this reversal is a result of confluence of several factors leading to the theoretically motivated observation that some unexpected processes in OT may be emergent. The paper also deals with another exceptional pattern where the combined outcome of vowel harmony and a morphological requirement of avoiding vowel-vowel sequences results in an exceptional pattern of syllabification. Contextualising these occurrences to the need for indexed markedness constraints, it is shown that the indexation of *HIATUS is able to analyse these occurrences. Furthermore, it is shown that hiatus avoidance can be the result of varying markedness requirements and it need not be the result of a single motivation of unmarkedness dictated by the overarching grammatical structure. *HIATUS is satisfied by both epenthesis as well as vowel deletion, and in one instance a morpheme even prefers a hiatal situation over non-hiatus. The exceptional occurrences show that markedness requirements and reversals may be often emergent, and therefore a result of a particular relation that a specific morpheme construes to be the least marked