Presentation
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Speech motor planning in monosyllabic and disyllabic pseudoword production
Poster A69 in Poster Session A, Tuesday, October 24, 10:15 am - 12:00 pm CEST, Espace Vieux-Port
Monica Lancheros1, Marina Laganaro1; 1University of Geneva
Speech planning processes include the retrieval of motor codes from a mental store. Some psycholinguistic models have proposed the syllable to be the functional unit explicitly represented in such centre of storage, also called syllabary (Levelt, Roelofs, and Meyer, 1999). Although many studies have brought evidence suggesting that speakers in fact retrieve stored syllabic units (e.g. Carreiras & Perea, 2004; Cholin, Levelt, & Schiller, 2006), it remains unclear how the syllabic retrieval is achieved during the production of multisyllabic utterances. More specifically, are all syllables retrieved in advance before actual production begins, or is only the first syllable retrieved prior to its production while subsequent syllables are planned during the articulation of the initial syllables? To unravel these mechanisms, in the present study we examine the brain dynamics underlying the production of monosyllabic and disyllabic pseudowords (i.e. /pra/ or /prati/, respectively) by means of electroencephalography (EEG). In order to target speech planning processes, pseudowords were produced in a delayed paradigm, upon the presentation of a response cue. Event-related potentials (ERPs) were aligned to the participants’ vocal onset (1) backwards (i.e. -300 ms preceding the vocal onset), to investigate if the initial syllable composing disyllabic pseudowords are similarly planned as monosyllabic pseudowords before the actual production, and (2) forward (i.e. 200 ms following the vocal onset, corresponding to the minimal duration of the first syllable), to capture potential neural differences between the actual production of monosyllabic pseudowords and that of the first syllable of disyllabic pseudowords. Preliminary results on seventeen participants revealed no differences between monosyllabic and disyllabic pseudowords in terms of accuracy (93% and 95%, respectively) or reaction times (658 ms and 667 ms, respectively). Despite the absence of behavioral differences, ERPs uncovered significant differences in the global dissimilarity index and in the distribution of the same topographies between monosyllabic and disyllabic pseudowords in three time-windows prior to the vocal onset (i.e. from -35 to -61 ms, from -84 to -104 ms and, from -240 to -256 ms). No differences were found between the two types of pseudowords from the initialization of vocalization onwards. Those preliminary results suggest that differences in speech motor planning between monosyllabic and disyllabic pseudowords are evident solely before the actual vocalization takes place. Thus, the retrieval of both syllables comprising the disyllabic pseudowords is achieved prior to the vocal onset, instead of the second syllable being retrieved during the production of the first one. We plan to conduct further analysis on these results using alternative approaches. Additionally, we aim to increase the participant pool by October to enhance the robustness of our findings. Carreiras, M., & Perea, M. (2004). Naming pseudowords in Spanish: Effects of syllable frequency. Brain and Language, 90(1-3), 393-400. Cholin, J., Levelt, W. J., & Schiller, N. O. (2006). Effects of syllable frequency in speech production. Cognition, 99(2), 205-235. Levelt, W. J., Roelofs, A., & Meyer, A. S. (1999). A theory of lexical access in speech production. Behavioral and brain sciences, 22(1), 1-38.
Topic Areas: Speech Motor Control, Language Production