Increasing Motivation Increases Intelligibility Benefits of Perceptual Training in Dysarthria.

Abstract

Perceptual training offers a promising, listener-targeted option for improving intelligibility of dysarthric speech. Cognitive resources are required for learning, and theoretical models of listening effort and engagement account for a role of listener motivation in allocation of such resources. Here, we manipulate training instructions to enhance motivation to test the hypothesis that increased motivation increases the intelligibility benefits of perceptual training. Across two data collection sites, which differed with respect to many elements of study design including age of speaker with dysarthria, dysarthria type and severity, type of testing and training stimuli, and participant compensation, 84 neurotypical adults were randomly assigned to one of two training instruction conditions: enhanced instructions or standard instructions. Intelligibility, quantified as percent words correct, was measured before and after training. Listeners who received the enhanced instructions achieved greater intelligibility improvements from training relative to listeners who received the standard instructions. This result was robust across data collection sites and the many differences in methodology. This study provides evidence for the role of motivation in improved understanding of dysarthric speech-increasing motivation increases allocation of cognitive resources to the learning process, resulting in improved mapping of the degraded speech signal. This provides empirical support for theoretical models of listening effort and engagement. Clinically, the results show that a simple addition to the training instructions can elevate learning outcomes.