Acoustic influences on part-of-speech decisions with category-ambiguous words

Nouns have longer duration than verbs in production, in addition to a range of differences across different tasks. This study examines factors predicting part-of-speech decisions for category-ambiguous real words and nonce words, with a focus on vowel duration and response time. Stimuli were category-ambiguous real words (e.g. comb ) and phonologically similar nonce words (e.g. /boum/). Each word and nonce word had two forms, one with the vowel lengthened and one with the vowel shortened. Listeners heard the stimulus words in isolation and identified each one as sounding more like a noun or more like a verb. Stimuli with shorter vowels were more likely to be identified as verbs than as nouns, both for real words and nonce words. The study demonstrates use of phonetic details as cues to part of speech, both for real words and also for nonce words; even without any associated lexical item, phonetic detail seems to be associated with syntactic information. These results are analyzed with a connectionist model which includes part of speech as a dimension which links to phonetic detail. Listeners were also more likely to identify real word stimuli as verbs; the tendency decreases with longer response times. This result contributes another line of evidence for the role of part of speech in perceptual processing; in a task which does not require lexical access, verb functions seem to be accessed more rapidly than nouns.