Learning of spatial and temporal patterns in sequential hand movements.

Speed and accuracy in performing a complex movement sequence improve with practice. To examine how the temporal and spatial patterns of movement sequence are learned, the sequence of target locations and the consistency in the timing of target presentation were manipulated independently while subjects produced a series of visually guided hand movements. When the sequence of target locations and the timing of target presentation followed a consistent pattern, performance for a particular movement sequence improved with practice for both temporal and spatial movement parameters. However, when the same temporal and spatial patterns were recombined with a phase shift, there was a small but consistent deficit in performance. These results suggest that whereas spatial and temporal patterns in a learned movement sequence can be recombined flexibly, optimal performance is obtained for a specific spatio-temporal pattern of movement sequence. Whereas subjects were largely aware of the spatial and temporal patterns, they were unaware of the phase-shift, suggesting that learning of a specific spatio-temporal pattern was implicit.