Author Response

We thank Morris for her thoughtful commentary¹ on our study.² We concur with her in the observation that our study provides further support for the role that instructional sets or pretask instructions can play in enhancing the motor performance of individuals with Parkinson disease (PD).^3,4 Given the constellation of cognitive and movement symptoms common in people with PD, as well as the relationship of cognitive processes to movement control,⁵ it is important to recognize that many individuals with PD retain their capabilities to distinguish between differing instructions and to act upon those distinctions motorically (eg, to increase stride length upon request). Our study provides additional evidence that individuals with mild to moderate disease severity (in the present study, at Hoehn and Yahr levels II and III; in the study by Behrman et al,³ Hoehn and Yahr levels II and III and a few with level IV staging) can distinguish between specific instructions and produce movement nuanced to these instructional distinctions. Furthermore, evidence of instructional set effectiveness is consistent with a recent review that noted stronger support for gait-related physical therapy interventions that combined conventional physical therapy with the provision of external visual or auditory cueing than for conventional physical therapy alone in individuals with PD.⁶ It seems reasonable to suggest that future refinements in physical therapy interventions for people with PD may be enhanced by recognition of the potential …