The role of feedback in speech motor learning : insights from healthy speakers and applications to the treatment of apraxia of speech
- Author(s): Austermann-Hula, Shannon Noelle
- et al.
Feedback is considered one of the most important variables in motor learning. The method of its application, however, can determine whether it exerts positive or negative influences on different aspects of motor control and learning. Thus, a principled approach must govern its use, particularly in the treatment of motor impairments. This dissertation examined the effects of theory-driven feedback manipulations on treatment of the speech motor programming disorder apraxia of speech (AOS). Motor learning research shows that delaying or reducing the frequency of feedback promotes retention and transfer of skills. In contrast, immediate or frequent feedback may temporarily enhance performance during acquisition, yet interfere with learning. The first two experiments in this dissertation tested these predictions in the context of a common treatment for AOS. The results provided evidence that reducing or delaying feedback provision promotes learning in some individuals with AOS, but also raised questions about how to determine which feedback manipulations provide optimal learning conditions for particular individuals. The general motor learning literature has shown that allowing learners to control their own feedback schedules facilitates learning, suggesting that it enables learners to receive feedback when they need it. Experiments 3 and 4 extended these notions to speech motor programming and learning in healthy speakers and those with AOS. Results from healthy speakers indicated that learner-controlled feedback manipulations affected different stages and aspects of motor programming (i.e., the translation of language units to speech motor commands), and that the benefits of learner-controlled feedback may be related to promotion of self-evaluation skills. Results from speakers with AOS provided qualified support for the application of learner- controlled feedback to the treatment of this disorder and provide impetus for further investigation. Overall, this research has demonstrated that individuals with AOS benefit from structured intervention, and that it is important to consider the influence of feedback variables when implementing AOS treatment. It has also demonstrated that the speech motor control system may share properties in common with general motor control, and that by extending general motor principles to the speech domain, we may increase our understanding of normal and disordered speech motor control and learning