Why spread? Kalabari clitics spread their tone due to word-minimality, prosodic constituency, and *LHH tonotactics

Abstract

Why do certain morphemes spread their tones, while other morphemes do not? We address this fundamental question in Kalabari (Kalaḅarị-Ịjọ), where certain clitics trigger a process of ‘low tone spread’ targeting following high tones (e.g. à ‘I’ in /à páḅụ́rụ́tẹ́ꜜẹ́/→[à pàḅụ̀rụ̀tẹ́ꜜẹ́]‘I have stammered’). We provide a comprehensive description of this process, establishing that its only triggers are a small class of prosodically-deficient pronominal clitics, all of which are low-toned, monosyllabic, and onsetless. We claim that these properties together prevent it from being parsed as a separate phonological word, and instead, the low tone of these clitics must tonally incorporate into a neighboring prosodic domain. We argue that the domain for low tone spread is the phonological phrase and show independent evidence for this exact constituent from grammatical tone. Finally, low tone spread is unbounded and targets a contiguous string of high tones within the relevant domain. We attribute its unboundedness to a consequence of tonal incorporation: this creates new LHH sequences which are independently marked in the language and consequently repaired by low tone spread. In total, our study demonstrates that tone spreading can profitably be decomposed into several sub-operations triggered by multiple interacting factors (here, word-minimality, prosodic constituency, and *LHH tonotactics).