A Novel Investigation of Generalized Motor Program Theory: Syllable Stress as a Motor-Class Variable.

Purpose: This experiment evaluated syllable-stress position as a motor class directed by a syllable-sized generalized motor program. Reaction times were predicted to be slower for stimuli with untrained stress patterns outside the trained motor class. Furthermore, reaction times were predicted to be stable for untrained stimuli within the same motor class regardless of phonetic similarity.

Method: Twenty-three young adults with typical speech and hearing participated in a motor-learning study comprised of motor-class training and a judgment task. Reaction times derived from the judgment task were evaluated using a within-subject repeated-measures design to evaluate the effects of syllable-stress position on stimulus type.

Results: Reaction times were not significantly different across proposed syllable-stress motor-class boundaries. However, reaction times for the stimuli within the same motor class were significantly different. To be specific, slower reaction times were associated with untrained stimuli that were phonetically similar to the trained stimuli.

Conclusions: The proposed hypotheses for syllable stress as a motor class were not met. Results indicate that multiple stimulus features, including syllable stress and phoneme similarity, may be encoded into memory during motor learning. Future research should evaluate how phonetic similarity of stimuli may influence motor-learning outcomes.

Supplemental Material: https://doi.org/10.23641/asha.5116837.