Objective: To examine the effects of dyad training protocol with different observation-durations on the learning of bimanual cup stacking in individuals with chronic stroke
Material and Method: Participants (experimental and control groups) completed the task in pairs. On the first day (acquisition phase: AP), the experimental group observed their partner 6 minutes and alternately performed the task 6 minutes for 4 sessions. The control group underwent 1 minute of observing alternated with 1 minute of performing the task for 24
sessions. On the following day (retention phase: RP), both groups performed the task individually first without feedback,
followed by with feedback. The dependent measures were movement time (MT), a measure of motor execution, and reaction time (RT), a measure of motor planning.
Results: In the AP, both groups completed the task with decreased MT. The experimental group showed significantly greater improvement of MT than the control group. As for RP, only the experimental group performed the task with less MT when compared with the last block of AP. Additionally, this group significantly decreased MT when compared with the first block. Although, a similar pattern was observed of decreased RT for both groups, in the RP, the experiment group had shorter RT
compared with that of the control group.
Conclusion: For individuals with chronic stroke, compared with the 1-minute observation alternating with physical practice,
the 6-minute duration resulted in greater persistent learning. Moreover, the 6-minute duration greatly enhanced the planning
of bimanual cup stacking.

Keywords: Action observation, Bimanual task, Dexterity, Mirror neuron system