A single robotic session that guides or increases movement error in survivors post-chronic stroke: which intervention is best to boost the learning of a timing task? 
Timing deficits can have a negative impact on the lives of survivors post-chronic stroke.  Studies evaluating ways to improve timing post stroke are scarce.  The goal of the study was to evaluate the impact of a single session of haptic guidance (HG) and error amplification (EA) robotic training interventions on the improvement of post-stroke timing accuracy.  Thirty-four survivors post-chronic stroke were randomly assigned to HG or EA.  Participants played a computerized pinball-like game with their affected hand positioned in a robot that either helped them perform better (HG) or worse (EA) during the task.  A baseline and retention phase preceded and followed HG and EA, respectively, in order to assess their efficiency at improving absolute timing errors.  The impact of the side of the stroke lesion on the participants' performance during the timing task was also explored for each training group.  An improvement in timing performance was only noted following HG (8.9 ± 4.9 ms versus 7.8 ± 5.3 ms, p = 0.032).  Moreover, for the EA group only, participants with a left-sided stroke lesion showed a worsening in performance as compared to those with a right-sided stroke lesion (p = 0.001).  Helping survivors post-chronic stroke perform a timing-based task is beneficial to learning.  Future studies should explore longer and more frequent HG training sessions in order to further promote post stroke motor recovery.  Implications for Rehabilitation Timing is crucial for the accomplishment of daily tasks.  The number of studies dedicated to improving timing is scarce in the literature, even though timing deficits are common post stroke.  This innovative study evaluated the impact of a single session of haptic guidance-HG and error amplification-EA robotic training interventions on improvements in timing accuracy among survivors post chronic stroke.  HG robotic training improves timing accuracy more than EA among survivors post chronic stroke.