Speech planning happens before speech execution: Online reaction time methods in the study of apraxia of speech

Purpose: The purpose of this article is to present an argument for the use of online reaction time (RT) methods to the study of apraxia of speech (AOS) and to review the existing small literature in this area and the contributions it has made to our fundamental understanding of speech planning (deficits) in AOS. Method: Following a brief description of limitations of offline perceptual methods, we provide a narrative review of various types of RT paradigms from the (speech) motor programming and psycholinguistic literatures and their (thus far limited) application with AOS. Conclusion: On the basis of the review of the literature, we conclude that with careful consideration of potential challenges and caveats, RT approaches hold great promise to advance our understanding of AOS, in particular with respect to the speech planning processes that generate the speech signal before initiation. A deeper understanding of the nature and time course of speech planning and its disruptions in AOS may enhance diagnosis and treatment for AOS. Results: Only a handful of published studies on apraxia of speech have used reaction time methods. However, these studies have provided deeper insight into speech planning impairments in AOS based on a variety of experimental paradigms.