Fine Michael S, Thoroughman Kurt A
Department of Biomedical Engineering, Washington University, St. Louis, MO 63130, USA.
J Neurophysiol. 2007 Sep;98(3):1392-404. doi: 10.1152/jn.00196.2007. Epub 2007 Jul 5.
Humans can rapidly change their motor output to make goal-directed reaching movements in a new environment. Theories that describe this adaptive process have long presumed that adaptive steps scale proportionally with error. Here we show that while performing a novel reaching task, participants did not adopt a fixed learning rule, but instead modified their adaptive response based on the statistical properties of the movement environment. We found that as the directional bias of the force distribution shifted from strongly biased to unbiased, participants transitioned from an adaptive process that scaled proportionally with error to one that adapted to the direction, but not magnitude, of error. Participants also modified their response as the likelihood of the perturbation changed; as the likelihood decreased from 80 to 20% of trials, participants adopted an increasingly disproportional strategy. We propose that people can rapidly switch between learning processes within minutes of experiencing a novel environment.
人类能够迅速改变其运动输出，以便在新环境中做出目标导向的伸手动作。长期以来，描述这一适应性过程的理论一直假定适应性步骤与误差成比例缩放。在这里，我们表明，在执行一项新颖的伸手任务时，参与者并没有采用固定的学习规则，而是根据运动环境的统计特性修改了他们的适应性反应。我们发现，随着力分布的方向偏差从强烈偏向变为无偏向，参与者从一个与误差成比例缩放的适应性过程转变为一个适应误差方向但不适应误差大小的过程。参与者还随着扰动可能性的变化修改了他们的反应；随着可能性从试验的80%降至20%，参与者采用了越来越不成比例的策略。我们提出，人们在体验新环境几分钟内就能在学习过程之间快速切换。
