The function of lenition/fortition patterns: evidence from word segmentation

This talk presents experimental evidence bearing on the functional roots of lenition/fortition patterns. We focus on the characteristically-intervocalic lenition patterns of spirantization and voicing, which are attested in dozens of unrelated languages. One proposed explanation for such patterns is that they help listeners detect prosodic boundaries by minimizing auditory disruption internal to prosodic domains and maximizing it at prosodic boundaries. A basic premise of such accounts is that listeners are biased to posit boundaries in the vicinity of more fortis (e.g. unvoiced, plosive) consonants relative to their lenis (voiced, continuant) counterparts. We tested the prediction that lenition/fortition patterns reinforce segmentation by using an artificial-language word segmentation task. We hypothesized that subjects would more quickly and/or robustly learn repeating units (‘words’) in artificial languages with lenition-like phonetic patterns than in languages with non-lenition-like patterns. The first two experiments confirmed this prediction for spirantization but not for voicing. We proposed post-hoc that this may be because consonant duration is a more important factor in 'voicing' lenition than voicing per se. A third experiment, currently being analyzed, attempts to test this hypothesis by simultaneously manipulating voicing and duration.