Donders Institute for Brain, Cognition, and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands.
Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
PLoS One. 2018 Jul 6;13(7):e0199544. doi: 10.1371/journal.pone.0199544. eCollection 2018.
Many sensorimotor activities have a time constraint for successful completion. In this case, any time devoted to sensory processing is at the expense of time available for motor execution. Earlier studies have explored how this competition between sensory processing and motor execution is resolved by using experimental designs that segregate the sensing and acting phase of the task. It was found that participants switch from the sensing to the acting stage such that the overall (sensorimotor) uncertainty in the outcome of the task is minimized. An unexplained observation in these studies is the substantial variability in switching times. We investigated the variability in switching time by correlating it with the underlying sensorimotor uncertainty. To this end, we used a modified version of the virtual ball catching paradigm proposed by Faisal & Wolpert (2009). Subjects were instructed to catch a ball, but as soon as they initiated their movement the ball disappeared. We extended the range of horizontal velocities and used two different start positions of the ball to quantify the dependence of sensory uncertainty on ball velocity. Velocity dependence of sensory uncertainty allowed us to manipulate sensory uncertainty and hence the sensorimotor uncertainty. We found that the variability in switching times is correlated with two factors. Firstly, variability in switching times is greater when variation in switching time has only minimal effects on sensorimotor uncertainty. Secondly, variability in switching times is greater when the sensorimotor uncertainty is larger. Our results suggest that the variability in switching time reflects an uncertainty-driven exploratory process.
许多感觉运动活动都有成功完成的时间限制。在这种情况下，任何用于感觉处理的时间都要以可用于运动执行的时间为代价。早期的研究已经探索了如何通过使用将任务的感知和执行阶段分开的实验设计来解决这种感觉处理和运动执行之间的竞争。研究发现，参与者从感知阶段切换到执行阶段，以便使任务结果的整体（感觉运动）不确定性最小化。这些研究中一个未解释的观察结果是切换时间的大量可变性。我们通过将其与潜在的感觉运动不确定性相关联来研究切换时间的可变性。为此，我们使用了 Faisal 和 Wolpert（2009 年）提出的虚拟球接球范式的修改版本。要求受试者接球，但一旦他们开始移动，球就会消失。我们扩展了水平速度范围，并使用球的两个不同起始位置来量化感觉不确定性对球速度的依赖性。感觉不确定性的速度依赖性使我们能够操纵感觉不确定性，从而操纵感觉运动不确定性。我们发现，切换时间的可变性与两个因素相关。首先，当切换时间的变化对感觉运动不确定性的影响最小时，切换时间的可变性更大。其次，当感觉运动不确定性较大时，切换时间的可变性更大。我们的结果表明，切换时间的可变性反映了一种不确定性驱动的探索过程。
