317-330 Ranganathan July 09.indd

The authors examined the influence of knowledge of results (KR) and concurrent feedback (ConFB) on coordination strategies in learning a 2-finger discrete force-production task. In Experiment 1, 4 groups learned the task under the following feedback regimes: ConFB, ConFB with knowledge of no-KR test (ConFB test information), KR after every trial (100% KR), and KR after every alternate trial (50% KR). Results show that the ConFB group had lower errors during acquisition but the highest errors in the no-KR transfer test. An uncontrolled manifold analysis showed that participants in the ConFB group adopted a strategy that tended to use multiple solutions to achieve the goal during acquisition, but they could not retain this strategy in the noKR test. Both KR groups retained the same coordination strategy from acquisition into the transfer test, even though this strategy was not conducive to producing a constant force. In Experiment 2, the authors observed these differences even when the time-to-peak force between the groups was constrained to a criterion bandwidth. These results show that ConFB facilitates using different solutions from trial to trial to achieve the same goal, and this may be a reason for poor performance when feedback is removed.