The ability of rapidly adapting our motor behaviour in order to face the unpredictable changes in the surrounding environment is fundamental for survival. To achieve such a high level of efficiency our motor system has to assess continuously the context in which it acts, gathering all available information that can be relevant for planning goal-oriented movements. One still-debated aspect of movement organization is the nature and timing of motor planning. While motor plans are often taken to be concerned with the setting of kinematic parameters as a function of perceptual and motor factors, it has been suggested that higher level, cognitive factors may also affect planning. To explore this issue further, we asked 18 right-handed human participants to perform speeded hand-reaching movement toward a visual target in two different experimental settings, a reaction time (RT) paradigm (go-only task) and a countermanding paradigm. In both tasks participants executed the same movements, but in the countermanding task no-stop trials were randomly intermixed with stop trials. In stop trials participants were required to withhold the ongoing movement whenever a stop signal was shown. It is known that the presence of stop trials induces a consistent increase of the RTs of no-stop trials with respect to the RTs of go-only trials. However, nothing is known about a similar effect for movement times (MTs). We found that RTs and MTs exhibit opposing tendencies, so that a decrease in the RT correspond to an increase in the MT and vice versa. This tendency was present in all our participants and significant in 90% of them. Furthermore we found a moderate, but again very consistent, anticorrelation between RTs and MTs on a trial-by-trial base. These findings are consistent with strategic changes in movement programmes for the very same movements under different cognitive contexts, requiring different degrees of feedback-driven control during movement.

中文翻译：

---

语境对伸手动作的准备和执行的影响

快速适应我们的运动行为以面对周围环境中不可预测的变化的能力是生存的基础。为了实现如此高的效率，我们的运动系统必须不断评估其动作的环境，收集所有与规划目标导向运动相关的可用信息。运动组织的一个仍有争议的方面是运动计划的性质和时间安排。虽然运动计划通常被认为与作为感知和运动因素的函数的运动学参数的设置有关，但有人提出更高水平的认知因素也可能影响计划。为了进一步探讨这个问题，我们要求 18 名惯用右手的人类参与者在两种不同的实验环境中，即反应时间 (RT) 范式（仅执行任务）和撤回范式，向视觉目标执行快速伸手动作。在这两项任务中，参与者执行相同的动作，但在撤销任务中，不间断试验随机与停止试验混合。在停止试验中，只要显示停止信号，参与者就必须停止正在进行的运动。众所周知，停止试验的存在会导致不间断试验的 RT 相对于仅进行试验的 RT 持续增加。但是，对于移动时间 (MT) 的类似影响，我们一无所知。我们发现 RT 和 MT 表现出相反的趋势，因此 RT 的减少对应于 MT 的增加，反之亦然。这种倾向存在于我们所有的参与者中，并且在 90% 的参与者中很显着。此外，我们在逐个试验的基础上发现 RT 和 MT 之间存在适度但又非常一致的反相关性。这些发现与不同认知环境下相同运动的运动计划的战略变化一致，在运动过程中需要不同程度的反馈驱动控制。