Uniqueness Point Effects during Speech Planning in Adults Who Do and Do Not Stutter

Abstract

Background/Aims: Previous studies employing a variety of tasks have demonstrated that adults who stutter (AWS) pre­sent with phonological encoding differences compared to adults who do not stutter (AWNS). The present study examined whether atypical preverbal monitoring also influenced AWS performance during one such paradigm – the silent phoneme monitoring task. Specifically, we investigated whether monitoring latencies for AWS were accelerated after the word’s uniqueness point – the phoneme that isolates the word from all lexical competitors – as observed for AWNS when monitoring internal and external speech. Methods: Twenty adults (10 AWS, 10 AWNS) completed a silent phoneme monitoring task using stimuli which contained either (a) early uniqueness points (EUP), (b) late uniqueness points, or (c) no uniqueness point (NUP). Response latency when identifying word-final phonemes was measured. Results: AWNS exhibited the expected uniqueness point effect when monitoring internal speech; word-final phonemes were accessed more rapidly for words with EUP than NUP. In contrast, AWS did not differ in the phoneme monitoring speed. That is, AWS did not exhibit the expected uniqueness point effects. Conclusion: Findings suggest that inefficient or atypical preverbal monitoring may be present in AWS and support theories that implicate the internal speech monitor as an area of deficit.