Implicit Motor Sequence Learning in Adults with and Without Developmental Coordination Disorder (DCD)

Objectives Even though individuals who have DCD may have difficulties learning a motor skill, few studies have investigated the mechanisms involved. Understanding these mechanisms and whether individuals with DCD show selective deficits would be of theoretical and practical interest. This study examined implicit motor sequence learning in adults with and without DCD using a serial response time (SRT) task. Methods Eleven participants with DCD (according to the DSM-5 criteria) and 18 participants without DCD matched for age, gender and handedness completed a version of the serial response time (SRT) task. Following this, a free generation task (FGT) assessed explicit sequence knowledge. Results Both groups were able to complete the SRT task and showed comparable accuracy. A Condition x Block interaction for response time (RT) data during the learning phase was explained by a failure of the DCD group to improve their performance, while the control group showed the typical learning effect of gradually faster RTs. Responses on the FGT revealed that the DCD group also acquired significantly less sequence knowledge than the control group during the task. Controlling for the development of sequence knowledge across the two groups still revealed an implicit learning deficit in the DCD group. Conclusions Adults with DCD failed to demonstrate the typical signs of implicit (procedural) learning on an established and influential sequence learning task. In addition, difficulties in acquiring task-related knowledge may point towards multiple difficulties in learning motor skills.