The Varying Effects of Dual Tasks on the Performance of Motor Skills across Practice

Numerous previous studies using the dual-task methodology have indicated that the effect of attentional direction on the performance of motor skill differs as a function of skill levels. Whereas previous studies relied mostly on inter-individual comparisons, this study focused on how the effects of different attentional conditions change within individuals with practice. Participants were instructed to learn a short and a long keying sequence (three versus six keys) and then practiced under two block-wise alternating dual-task conditions. In each trial, a tone, either low- or high-pitched, was presented at one of the three/six keys and participants had to indicate either the pitch of the tone (extraneous dual task) or the key with which the tone was presented (skill-focused dual task) after finishing the execution of the keying sequence. Motor task performance was assessed by reaction time (RT) and movement duration (MD), and the concurrent cognitive task performance was assessed by the error rate. RT was faster in the skill-focused dual-task condition at the beginning of practice, whereas a generally shorter MD was found in the extraneous dual-task condition. The error rate in the extraneous dual task decreased with practice, whereas in the skill-focused dual task, it increased with practice. These results show that the effects of attentional direction differ not only as a function of the amount of practice but also as a function of the stage of information processing. Furthermore, our results indicate that the direction of attention alone does not explain the different patterns of performance at different skill levels seen across dual-task studies; rather, the skill levels, the nature of cognitive demands, the difficulty level of dual tasks, and the complexity of the motor skill could all drive performance differences.