Data from: Pupil-linked arousal determines variability in perceptual decision making

Decision making between several alternatives is thought to involve the gradual accumulation of evidence in favor of each available choice. This process is profoundly variable even for nominally identical stimuli, yet the neuro-cognitive substrates that determine the magnitude of this variability are poorly understood. Here, we demonstrate that arousal state is a powerful determinant of variability in perceptual decision making. We measured pupil size, a highly sensitive index of arousal, while human subjects performed a motion-discrimination task, and decomposed task behavior into latent decision making parameters using an established computational model of the decision process. In direct contrast to previous theoretical accounts specifying a role for arousal in several discrete aspects of decision making, we found that pupil diameter was uniquely related to a model parameter representing variability in the rate of decision evidence accumulation: Periods of increased pupil size, reflecting heightened arousal, were characterized by greater variability in accumulation rate. Pupil diameter also correlated trial-by-trial with specific patterns of behavior that collectively are diagnostic of changing accumulation rate variability, and explained substantial individual differences in this computational quantity. These findings provide a uniquely clear account of how arousal state impacts decision making, and may point to a relationship between pupil-linked neuromodulation and behavioral variability. They also pave the way for future studies aimed at augmenting the precision with which people make decisions.学界普遍认为，在多项备选方案间开展决策的过程，涉及逐步积累支撑各可选选项的证据。即便面对名义上完全相同的刺激，该过程仍存在高度变异性，但目前学界对决定该变异幅度的神经认知基础（neuro-cognitive substrates）仍知之甚少。本研究证实，唤醒状态（arousal state）是感知决策变异性的一个强力决定因素。我们在人类被试完成运动辨别任务（motion-discrimination task）时，测量了作为唤醒状态高敏感指标的瞳孔大小，并借助已被广泛验证的决策过程计算模型，将任务行为拆解为潜在决策参数（latent decision making parameters）。与此前认为唤醒状态仅作用于决策若干离散维度的理论阐释截然相反，我们发现瞳孔直径仅与代表决策证据积累速率变异性的模型参数相关：瞳孔直径增大的时段（对应唤醒水平提升），其积累速率的变异性也更高。此外，瞳孔直径还与逐试次（trial-by-trial）的特定行为模式存在相关性，这些行为模式整体可作为积累速率变异性动态变化的诊断依据，同时该指标也解释了该计算指标上存在的显著个体差异。本研究结果清晰阐释了唤醒状态如何影响决策过程，同时也为揭示与瞳孔相关的神经调节（pupil-linked neuromodulation）与行为变异性之间的关联提供了线索。该研究也为后续旨在提升人类决策精度的相关研究铺平了道路。