Wellcome Trust Centre for Neuroimaging, Institute of Neurology, University College London, London WC1N 3BG, United Kingdom.
J Neurosci. 2010 Oct 27;30(43):14380-9. doi: 10.1523/JNEUROSCI.1459-10.2010.
Making the best choice when faced with a chain of decisions requires a person to judge both anticipated outcomes and future actions. Although economic decision-making models account for both risk and reward in single-choice contexts, there is a dearth of similar knowledge about sequential choice. Classical utility-based models assume that decision-makers select and follow an optimal predetermined strategy, regardless of the particular order in which options are presented. An alternative model involves continuously reevaluating decision utilities, without prescribing a specific future set of choices. Here, using behavioral and functional magnetic resonance imaging (fMRI) data, we studied human subjects in a sequential choice task and use these data to compare alternative decision models of valuation and strategy selection. We provide evidence that subjects adopt a model of reevaluating decision utilities, in which available strategies are continuously updated and combined in assessing action values. We validate this model by using simultaneously acquired fMRI data to show that sequential choice evokes a pattern of neural response consistent with a tracking of anticipated distribution of future reward, as expected in such a model. Thus, brain activity evoked at each decision point reflects the expected mean, variance, and skewness of possible payoffs, consistent with the idea that sequential choice evokes a prospective evaluation of both available strategies and possible outcomes.
当面临一系列决策时，做出最佳选择需要一个人同时判断预期结果和未来行动。尽管经济决策模型在单一选择情境中考虑了风险和回报，但关于序列选择的类似知识却很少。经典的基于效用的模型假设决策者选择并遵循一个最佳的预定策略，而不考虑选项呈现的特定顺序。另一种模型涉及不断重新评估决策效用，而不规定特定的未来选择集。在这里，我们使用行为和功能磁共振成像 (fMRI) 数据研究了在序列选择任务中的人类受试者，并使用这些数据比较了价值评估和策略选择的替代决策模型。我们提供的证据表明，受试者采用了一种重新评估决策效用的模型，其中可用的策略在评估行动价值时会不断更新和组合。我们通过同时采集的 fMRI 数据验证了这个模型，表明序列选择引发了与预期未来奖励分布跟踪一致的神经反应模式，这符合这种模型的预期。因此，每个决策点引发的大脑活动反映了可能收益的预期均值、方差和偏度，这与序列选择引发对可用策略和可能结果的前瞻性评估的观点一致。
