School of Psychology, University of Aberdeen, Aberdeen, United Kingdom.
School of Psychology, University of Aberdeen, Aberdeen, United Kingdom.
Cognition. 2020 Dec;205:104426. doi: 10.1016/j.cognition.2020.104426. Epub 2020 Aug 14.
Current studies on visuomotor decision making come to inconsistent conclusions regarding the optimality with which these decisions are made. When executing rapid reaching movements under uncertainty, humans tend to automatically select optimal movement paths that take into account the position of all potential targets (spatial averaging). In contrast, humans rarely employ optimal strategies when making decisions on whether to pursue two action goals simultaneously or prioritise one goal over another. Here, we manipulated whether spatial averaging or pre-selection of a single target would provide the optimal strategy by varying the spatial separation between two potential movement targets as well as the time available for movement execution. In Experiment 1, we aimed to determine the time needed to reach for targets with small and large separation between them and to measure baseline strategies under low time pressure. Given generous time limits, participants did not employ a pure averaging approach but instead tended to pre-select the target that was easiest to reach and corrected their movement path in-flight if required. In Experiment 2, a strict time limit was set such that the optimal strategy to reach the correct target depended on the separation between the potential targets: for small separations, there was enough time to employ averaging strategies, but higher success for larger separations required pre-selecting the final target instead. While participants varied in the strategies they preferred, none of them flexibly adjusted their movement strategies depending on the spatial separation of the targets. In Experiment 3, we confirm the bias toward targets that are easiest to reach and show that this comes at the expense of overall task success. The results suggest a strong tendency for humans to minimize immediate movement effort and a general failure to adapt movement strategies flexibly with changes in the task parameters.
目前关于视动决策的研究对于这些决策的最优性得出了不一致的结论。当在不确定的情况下执行快速到达运动时，人类倾向于自动选择考虑所有潜在目标位置的最优运动路径（空间平均）。相比之下，人类在决定是否同时追求两个动作目标或优先考虑一个目标时，很少采用最优策略。在这里，我们通过改变两个潜在运动目标之间的空间分离以及运动执行的可用时间，来操纵空间平均或单个目标的预选是否会提供最优策略。在实验 1 中，我们旨在确定到达小间隔和大间隔目标所需的时间，并在低时间压力下测量基线策略。在时间充裕的情况下，参与者没有采用纯粹的平均方法，而是倾向于预选最容易到达的目标，并在需要时在飞行中修正其运动路径。在实验 2 中，设置了严格的时间限制，以便到达正确目标的最优策略取决于潜在目标之间的分离：对于小的分离，有足够的时间采用平均策略，但对于更大的分离，更高的成功率需要预选最终目标。虽然参与者在他们偏好的策略上有所不同，但没有人根据目标的空间分离灵活调整他们的运动策略。在实验 3 中，我们证实了人们倾向于选择最容易到达的目标，并且这种倾向是以整体任务成功率为代价的。结果表明，人类有一种强烈的倾向，即最小化即时运动努力，并且普遍无法根据任务参数的变化灵活调整运动策略。
