Effects of utterance length on word and phrase durations

Abstract

This study examined the effects of utterance length on word and phrase durations to investigate how the planned length of an utterance influences the rate of speech. An experiment was conducted in which the visual stimuli cued the production of sentences with one, two, or three subject noun phrases (NPs)—e.g., “Nine green rhinos and eight red weasels and eight blue llamas live in the zoo.” In addition, a novel, delayed stimuli condition was tested in which the visual stimuli that cued non-initial NPs (“eight red weasels and eight blue llamas”) were presented after participants started production, and thus sentence length changed after utterance initiation. Word and NP durations were analyzed. NP durations were longer in sentences with more NPs, and moreover, durational increases were primarily observed in the rightmost words of the NPs. These findings are important first because they show that the previously observed effects of number of words on word durations extend to phrases, and second because they show that phrase duration effects are localized to phrase ends. When the utterance length changed after the start of production, participants lengthened the end of the initial NP and the following conjunction to plan for the newly presented NPs.