To appear in Natural Language and Linguistic Theory Weak Triggers in Vowel Harmony

This paper examines vowel harmony initiated by a weak trigger. Height harmony in Veneto Italian dialects, wherein a post-tonic high vowel triggers raising of preceding mid vowels, forms a case study. Veneto presents two variable patterns: stresstargeted harmony, in which harmony propagates to the stressed syllable, and maximal extension harmony, in which raising persists to pretonic vowels. The conditions under which weak vowels trigger and control harmony are examined. It is argued that weak trigger harmony is motivated by perceptual disadvantage: harmony improves exposure of the spreading feature, accomplished either by extending to a stressed position or maximizing duration in the word. The apparent primacy of the vowel quality in weak position in Veneto is accounted for by markedness factors that independently prevent the stressed vowel from overriding it. In regard to positional privilege, it is argued that positional licensing (markedness) drives stress-targeted spreading – positional faithfulness is inappropriate to characterize strong targets. A weak trigger pattern emerges when licensing constraints operating over perceptually marked structure dominate positional faithfulness. Crosslinguistic applications are also explored.