A controlled clinical application of motor learning principles with apraxia of speech

Abstract

Adults with acquired apraxia of speech (AOS) often do not generalise effects of treatment to untreated speech behaviours. Recent studies suggest that using the principles of motor learning (PML) approach may optimise retention and generalisation in AOS. PML guide the structure of motor practice along with the frequency and type of feedback provided during practice. This study aimed to investigate the effects of order of stimulus presentation and feedback frequency, on the acquisition, retention, and generalisation of speech skills in persons with acquired AOS plus aphasia. Four participants with AOS participated in a crossover design with multiple baselines across behaviours to compare two sets of motor learning principles– random order of stimulus presentation with low frequency feedback (R-L) ), considered more beneficial for learning, versus blocked order with high frequency feedback, considered less beneficial. All participants demonstrated significantly improved performance with treated words for both treatment regimes, both throughout treatment and on retention probes. There was a trend for better retention for some participants following the R-L condition. Performance data from treatment sessions did not support more rapid acquisition under either regime. Three of four participants showed generalisation of treatment effects to untreated related words, regardless of treatment conditions. Consistent with previous studies, individuals with chronic AOS responded positively to articulation-based intervention. The limited difference between the treatment conditions tested here suggests that the practice schedule and feedback frequency may be less important than the amount of practice provided; although the interaction of these principles and treatment dosage with other factors such as disorder severity require further investigation.