Department of Psychology, Biological Psychology, University of Cologne, Cologne, Germany.
PLoS Comput Biol. 2022 Jun 10;18(6):e1010096. doi: 10.1371/journal.pcbi.1010096. eCollection 2022 Jun.
Value-based decision-making is of central interest in cognitive neuroscience and psychology, as well as in the context of neuropsychiatric disorders characterised by decision-making impairments. Studies examining (neuro-)computational mechanisms underlying choice behaviour typically focus on participants' decisions. However, there is increasing evidence that option valuation might also be reflected in motor response vigour and eye movements, implicit measures of subjective utility. To examine motor response vigour and visual fixation correlates of option valuation in intertemporal choice, we set up a task where the participants selected an option by pressing a grip force transducer, simultaneously tracking fixation shifts between options. As outlined in our preregistration (https://osf.io/k6jct), we used hierarchical Bayesian parameter estimation to model the choices assuming hyperbolic discounting, compared variants of the softmax and drift diffusion model, and assessed the relationship between response vigour and the estimated model parameters. The behavioural data were best explained by a drift diffusion model specifying a non-linear scaling of the drift rate by the subjective value differences. Replicating previous findings, we found a magnitude effect for temporal discounting, such that higher rewards were discounted less. This magnitude effect was further reflected in motor response vigour, such that stronger forces were exerted in the high vs. the low magnitude condition. Bayesian hierarchical linear regression further revealed higher grip forces, faster response times and a lower number of fixation shifts for trials with higher subjective value differences. An exploratory analysis revealed that subjective value sums across options showed an even more pronounced association with trial-wise grip force amplitudes. Our data suggest that subjective utility or implicit valuation is reflected in motor response vigour and visual fixation patterns during intertemporal choice. Taking into account response vigour might thus provide deeper insight into decision-making, reward valuation and maladaptive changes in these processes, e.g. in the context of neuropsychiatric disorders.
基于价值的决策是认知神经科学和心理学的核心关注点，也是神经精神疾病中决策障碍的研究重点。研究考察决策行为的（神经）计算机制通常侧重于参与者的决策。然而，越来越多的证据表明，选项估值也可能反映在运动反应活力和眼动中，这是主观效用的内隐测量。为了研究跨期选择中选项估值与运动反应活力和视觉注视的关系，我们设计了一项任务，参与者通过按压握力传感器来选择一个选项，同时跟踪选项之间的注视转移。正如我们的预注册（https://osf.io/k6jct）中所述，我们使用分层贝叶斯参数估计来对假设双曲线折扣的选择进行建模，比较了软最大化和漂移扩散模型的变体，并评估了反应活力与估计模型参数之间的关系。行为数据通过指定漂移率与主观价值差异呈非线性关系的漂移扩散模型得到了最好的解释。复制先前的发现，我们发现了时间折扣的幅度效应，即较高的奖励折扣较小。这种幅度效应进一步反映在运动反应活力中，即高幅度条件下的力更强。贝叶斯分层线性回归进一步揭示了更高的握力、更快的反应时间和更低的注视转移次数，用于具有更高主观价值差异的试验。探索性分析表明，选项之间的主观价值总和与试验级握力振幅的关联更为明显。我们的数据表明，主观效用或隐式估值反映在跨期选择中的运动反应活力和视觉注视模式中。考虑反应活力可能会深入了解决策、奖励估值以及这些过程中的适应不良变化，例如在神经精神疾病的背景下。
