Learning complex upper-limb movements through practicing movement elements.

Upper-limb complex movements constitute a major part of our daily activities. Research shows complex movements are generated by sequences of movement elements represented by a unimodal bell-shaped velocity curve. We utilized this understanding in the field of motor skill acquisition and hypothesized that practicing a movement element of a complex movement trajectory will facilitate the performance on the respective complex movement trajectory. To test this, we designed an experiment where the control group learned a full complex trajectory, whereas the two elemental groups learned two different movement elements of the complex trajectory. The two main outcome measures explaining the performance were accuracy and speed. The elemental groups, after training on movement elements, significantly improved their speed and accuracy when tested on the full complex trajectory. The result illustrated that training on a movement element of a complex trajectory benefited the performance of the full complex trajectory. The two elemental groups showed similar improvements in the performance of the complex motor skill, despite obtaining training on different movement elements of the same complex movement. The findings show that complex movements can be learned by practicing their movement elements.