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Speed Accuracy Relationships in Speech Motor Behavior
Stephen M. Tasko

Speakers routinely vary speech rate to simultaneously meet communication demands and temporal constraints. Although the same message can be effectively transmitted at a variety of rates, speaking too fast can compromise intelligibility and slowing down is a commonly used strategy to enhance speech clarity. This suggestion that “fast” motor events are more likely to be “less accurate” motor events is very familiar to students of limb motor behavior. This relationship, referred to as the “speed-accuracy trade-off”, predicts that movement speed is systematically related to the variability in reaching a prescribed target. Its ubiquity across a wide variety of conditions designates it a one of the fundamental principles of simple movement. It is less certain if such a principle governs speech motor behavior. This study was designed to evaluate if such a principle operates in the speech motor system. Speakers produced a number of vowel transitions that varied in the duration and extent of the transition. It was predicted that, consistent with the speed-accuracy trade-off, an increase in the rate of the vowel transition would be associated with an increase in acoustic and kinematic variability. Results will be compared to findings reported for other motor systems.

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