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Motor experiences rather than sensory errors mediate the update in speech production
Poster C38 in Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 4
Yuhan Lu1,2, Xing Tian1,2; 1New York University Shanghai, 2NYU-ECNU Institute of Brain and Cognitive Science
Introduction: The ability to produce speech accurately is a fundamental adaptive behavior and vital in communication. The efficient control of speech production requires detecting sensory errors in speech feedback and generating motor compensatory responses to correct the errors. It remains in debate whether the past sensory errors or the history of motor compensation are weighted more in regulating naturalistic speech production. Methods: Using a serial-dependency paradigm, we introduce auditory feedback perturbation with random amounts in a sequence of trials. We quantified the systematic biases of the motor compensation amount in the current trial as a function of auditory feedback perturbation or motor compensation in the preceding trial. Results: In the first experiment when participants consistently produced the /a/ sound throughout trials, the motor compensation in the current trial was systematically attracted toward the compensation in the preceding trial rather than auditory feedback perturbation. The relationship between the current compensation and the last compensation formed a derivative-of-Gaussian-shaped curve. Next, we investigated whether this attractive bias occurred between different vowel categories. In the second experiment, participants produced different vowels in each trial. The attractive bias of motor compensation was significant even when adjacent trials were different vowels. The effect was smaller than that when the same vowels were in adjacent trials. Finally, we tested the attractive bias of motor compensation both within and across syntactic boundaries. Participants produced a four-syllable sentence with a noun phrase in the first two syllables followed by a verb phrase in the last two syllables. In the within-boundary condition, auditory feedback perturbation was applied to the first or third syllable, and we measured the attractive bias in the next syllable within the same phrase. In the across-boundary condition, perturbation was applied to the second syllable, and we measured the attractive bias in the next syllable across phrases. The attractive bias of motor compensation was stronger within boundaries than across boundaries. Summary: Collective results from a series of speech production studies that vary at phonological and syntactic levels consistently support that motor experiences mediate the adaption in subsequent vocal production. The attractive bias from past compensation depends on adjacent vowels and syntactic boundaries.
Topic Areas: Speech Motor Control, Language Development/Acquisition