title: Feedback delays eliminate auditory-motor learning in speech production.
abstract: Neurologically healthy individuals use sensory feedback to alter future movements by updating internal models of the effector system and environment. For example, when visual feedback about limb movements or auditory feedback about speech movements is experimentally perturbed, the planning of subsequent movements is adjusted - i.e., sensorimotor adaptation occurs. A separate line of studies has demonstrated that experimentally delaying the sensory consequences of limb movements causes the sensory input to be attributed to external sources rather than to one's own actions. Yet similar feedback delays have remarkably little effect on visuo-motor adaptation (although the rate of learning varies, the amount of adaptation is only moderately affected with delays of 100-200ms, and adaptation still occurs even with a delay as long as 5000ms). Thus, limb motor learning remains largely intact even in conditions where error assignment favors external factors. Here, we show a fundamentally different result for sensorimotor control of speech articulation: auditory-motor adaptation to formant-shifted feedback is completely eliminated with delays of 100ms or more. Thus, for speech motor learning, real-time auditory feedback is critical. This novel finding informs theoretical models of human motor control in general and speech motor control in particular, and it has direct implications for the application of motor learning principles in the habilitation and rehabilitation of individuals with various sensorimotor speech disorders.
authors: Department of Speech and Hearing Sciences, University of Washington, 1417 N.E. 42nd St. Seattle, WA 98105-6246, USA; Haskins Laboratories, 300 George St. Suite 900, New Haven, CT 06511, USA. Electronic address: LudoMax@uw.edu.
authors: Ludo
authors: L
authors: Max
authors: Department of Speech and Hearing Sciences, University of Washington, 1417 N.E. 42nd St. Seattle, WA 98105-6246, USA.
authors: Derek G
authors: DG
authors: Maffett
mesh_terms: D000161:Acoustic Stimulation; D056228:Feedback, Sensory; D005260:Female; D006801:Humans; D007858:Learning; D008297:Male; D013060:Speech; D013061:Speech Acoustics; D013067:Speech Perception; D013068:Speech Production Measurement; D055815:Young Adult
keywords: Feedback; Motor control; Motor learning; Sensorimotor adaptation; Speech production