Moss Rehabilitation Research Institute, Elkins Park, PA 19027
Department of Neuroscience, Holy Family University, Philadelphia, PA 19114.
eNeuro. 2022 Apr 12;9(2). doi: 10.1523/ENEURO.0503-21.2022. Print 2022 Mar-Apr.
When faced with multiple potential movement options, individuals either reach directly to one of the options, or initiate a reach intermediate between the options. It remains unclear why people generate these two types of behaviors. Using the go-before-you-know task (commonly used to study behavior under choice uncertainty) in humans, we examined two key questions. First, do these two types of responses actually reflect distinct movement strategies? If so, the relative desirability (i.e., weighing the success likelihood vs the attainable reward) of the two target options would not need to be computed identically for direct and intermediate reaches. We showed that indeed, when reward and success likelihood differed between the two options, reach direction was preferentially biased toward different directions for direct versus intermediate reaches. Importantly, this suggests that the computation of subjective values depends on the choice of movement strategy. Second, what drives individual differences in how people respond under uncertainty? We found that risk/reward-seeking individuals tended to generate more intermediate reaches and were more responsive to changes in reward, suggesting these movements may reflect a strategy to maximize reward versus success. Together, these findings suggest that when faced with choice uncertainty, individuals adopt movement strategies consistent with their risk/reward attitude, preferentially biasing behavior toward exogenous rewards or endogenous success and consequently modulating the relative desirability of the available options.
当面临多个潜在的运动选项时，个体要么直接伸向其中一个选项，要么在选项之间发起一个中间伸手动作。目前尚不清楚为什么人们会产生这两种行为。我们使用了人类中的“先做后知道”任务（常用于研究选择不确定性下的行为），研究了两个关键问题。首先，这两种类型的反应是否实际上反映了不同的运动策略？如果是这样，那么对于直接和中间伸手，两个目标选项的相对可取性（即权衡成功可能性与可获得奖励）无需以相同的方式计算。我们发现，当两个选项之间的奖励和成功可能性不同时，直接伸手和中间伸手的方向确实偏向于不同的方向。重要的是，这表明主观价值的计算取决于运动策略的选择。其次，是什么驱动了人们在不确定性下反应的个体差异？我们发现，风险寻求者倾向于产生更多的中间伸手动作，并且对奖励的变化更敏感，这表明这些动作可能反映了一种最大化奖励与成功的策略。总的来说，这些发现表明，当面临选择不确定性时，个体采用与风险/回报态度一致的运动策略，优先将行为偏向于外在奖励或内在成功，从而调节可用选项的相对可取性。
