Transfer of Learning: What Does It Tell Us About Speech Production Units?

Purpose: Words, syllables, and phonemes have each been regarded as basic encoding units of speech production in various psycholinguistic models. The present article investigates the role of each unit in the interface with speech articulation, using a paradigm from motor control research. Method: Seventy-six native speakers of French were trained to change their production of /be/ in response to an auditory feedback perturbation (auditory-motor learning). We then assessed the magnitude of learning transfer from /be/ to the syllables in 2 pseudowords (/bepe/ and /pebe/) and 1 real word (/bebe/) as well as the aftereffect on the same utterance (The/) with a between-subjects design. This made it possible to contrast the amplitude of transfer at the levels of the utterance, the syllable, and the phoneme, depending on the position in the word. Linear mixed models allowed us to study the amplitude as well as the dynamics of the transfer and the aftereffect over trials. Results: Transfer from the training utterance /be/ was observed for all vowels of the test utterances but was larger to the syllable /be/ than to the syllable /pe/ at word-initial position and larger to the 1st syllable than to the 2nd syllable in the utterance. Conclusions: Our study suggests that words, syllables, and phonemes may all contribute to the definition of speech motor commands. In addition, the observation of a serial order effect raises new questions related to the connection between psycholinguistic models and speech motor control approaches.