Poko postlexical tone requires serial, directional evaluation

Poko (Skou, PNG) displays a complex tone system, with three contrastive levels, toneless syllables, and floating tones. Lexical tone is characterized by robust patterns of anti-alignment, wherein H tones may not be initial and L tones may not be final (McPherson and Dryer, 2021; McPherson, 2022). This paper analyzes the postlexical realization of tone, especially the behavior of floating tones, rising tones, and toneless syllables. The Poko tone system shows unique twists on cross-linguistic patterns, such as the OCP, tone raising before L, and the avoidance of non-final rising tones. We demonstrate that the behavior of floating tones cannot be accounted for in a constraint-based theory with global evaluation, as in traditional Optimality Theory or Harmonic Grammar. Instead, the data motivate the use of directional Harmonic Serialism (Lamont, 2022b), wherein changes are made incrementally and directionally, thus avoiding the creation of ties among otherwise similar candidates.