Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom
Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, United Kingdom.
J Neurosci. 2020 Nov 11;40(46):8938-8950. doi: 10.1523/JNEUROSCI.2130-19.2020. Epub 2020 Oct 19.
Our ability to evaluate an experience retrospectively is important because it allows us to summarize its total value, and this summary value can then later be used as a guide in deciding whether the experience merits repeating, or whether instead it should rather be avoided. However, when an experience unfolds over time, humans tend to assign disproportionate weight to the later part of the experience, and this can lead to poor choice in repeating, or avoiding experience. Using model-based computational analyses of fMRI recordings in 27 male volunteers, we show that the human brain encodes the summary value of an extended sequence of outcomes in two distinct reward representations. We find that the overall experienced value is encoded accurately in the amygdala, but its merit is excessively marked down by disincentive anterior insula activity if the sequence of experienced outcomes declines temporarily. Moreover, the statistical strength of this neural code can separate efficient decision-makers from suboptimal decision-makers. Optimal decision-makers encode overall value more strongly, and suboptimal decision-makers encode the disincentive markdown (DM) more strongly. The separate neural implementation of the two distinct reward representations confirms that suboptimal choice for temporally extended outcomes can be the result of robust neural representation of a displeasing aspect of the experience such as temporary decline. One of the numerous foibles that prompt us to make poor decisions is known as the "Banker's fallacy," the tendency to focus on short-term growth at the expense of long-term value. This effect leads to unwarranted preference for happy endings. Here, we show that the anterior insula in the human brain marks down the overall value of an experience as it unfolds over time if the experience entails a sequence of predominantly negative temporal contrasts. By contrast, the amygdala encodes overall value accurately. These results provide neural indices for the dichotomy of decision utility and experienced utility popularized as by Daniel Kahneman.
我们能够对过往经历进行评估是非常重要的，因为它可以帮助我们总结这段经历的总体价值，而这个总结后的价值可以作为之后的决策依据，决定这段经历是否值得再次体验，或者是否应该避免。然而，当一段经历随着时间展开时，人类往往会对经历的后期赋予不成比例的权重，这可能导致在重复或避免体验方面做出不佳的选择。通过对 27 名男性志愿者的 fMRI 记录进行基于模型的计算分析，我们发现人类大脑在两个不同的奖励表示中对扩展序列的结果进行编码，以总结其价值。我们发现，在经历的结果序列暂时下降的情况下，杏仁核可以准确地编码整体体验价值，但如果激励性的前脑岛活动减少，其价值就会被过度贬低。此外，这种神经编码的统计强度可以将高效的决策者与非最佳决策者区分开来。最优决策者更强烈地编码整体价值，而非最佳决策者则更强烈地编码抑制性标记（DM）。这两个不同奖励表示的独立神经实现证实了，对于时间上扩展的结果的次优选择可能是对体验中不愉快方面（如暂时下降）的强有力的神经表示的结果。促使我们做出不佳决策的众多弱点之一是被称为“银行家谬误”的倾向，即关注短期增长而忽视长期价值。这种效应导致对美好结局的不合理偏好。在这里，我们发现，如果体验涉及主要负面时间对比的序列，人脑的前脑岛会随着时间的推移而降低体验的整体价值。相比之下，杏仁核准确地编码了整体价值。这些结果为丹尼尔·卡尼曼（Daniel Kahneman）提出的决策效用和体验效用二分法提供了神经指标。
