Reprogramming phonologically similar utterances: the role of phonetic features in pre-motor encoding

The effects of phonologic similarity on speech production latencies were investigated to explore the role of articulatory phonetic features and reprogramming operations during pre-motor stages of production. A form-based priming technique was used in five experiments to elicit rapid productions of single words. Subjects responded to visually presented pairs of minimally contrastive monosyllabic words, which varied with respect to the phonetic featural similarity of their onsets. Factors that were systematically manipulated across experiments included stimulus set size, duration of the interstimulus interval, and the use of feedback to subjects concerning their response latencies. Speech onset latencies obtained in a control condition in which no phonetic features were shared were compared to four other conditions in which the word initial phonemes of prime-target pairs did share features. Results revealed that shared manner was the most influential factor associated with the observed inhibitory phonologic similarity effect. In addition, smaller stimulus set size (6 words) yielded significantly slower overall response latencies than experiments employing larger stimulus sets (18 words). These findings suggested that inhibitory phonologic similarity effects did not stem from biomechanical constraints imposed by the articulatory system. Rather the methods employed in this investigation were supported as a means to investigate both the underlying units of representation and the processes involved in pre-motor planning apart from articulatory effects. The results of this investigation also supported the hypothesis that, during phonologic encoding, word form retrieval entails the selection and assembly of sublexical units into word form frames. No evidence of whole word retrieval during pre-motor encoding was obtained. The potential utility of this experimental paradigm in the investigation of pre-motor planning in disorders that putatively affect the processes involved in transforming word meaning into word form is also discussed.