Manual Rhythmic Sequencing Skills in Children With Childhood Apraxia of Speech

Purpose: Rhythm is one procedural mechanism that underlies language and motor skill acquisition and has been implicated in children with childhood apraxia of speech (CAS). The purpose of this study is to investigate manual rhythmic sequencing skills in children with a history of or current CAS (hx/CAS) compared to children with typical development (TD). Method: Thirty-eight children (18 with hx/CAS, 20 with TD), ages 5;0-12;8 (years; months), from across the United States participated in an online study. Participants imitated two rhythms in two different conditions, clapping and tapping. We assessed overall accuracy, mean number of beats, pause marking, and rhythmic sequence variability using the Mann--Whitney U test. Effect sizes were calculated to examine the influence of coordinative complexity on performance. Results: Compared to children with TD, children with hx/CAS marked fewer trials with a pause in both conditions of the easier rhythm and showed lower overall accuracy and more variable rhythmic sequences in both rhythms and conditions. The mean number of beats produced by children with hx/CAS and children with TD did not differ in three out of four rhythms/conditions. Unlike children with TD, children with hx/CAS showed little improvement from clapping to tapping across most dependent measures; reducing coordination demands did not improve performance in children with hx/CAS. Conclusions: We found that children with hx/CAS show manual rhythmic deficits that are similar to the deficits they display in speech. These findings provide support for a domain-general cognitive mechanisms account of the rhythmic deficits observed across linguistic and nonlinguistic tasks in children with hx/CAS.