Cash-Padgett Tyler, Azab Habiba, Yoo Seng Bum Michael, Hayden Benjamin Y
Department of Neuroscience and Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, 55455, USA.
Department of Brain and Cognitive Sciences and Center for Visual Sciences, Center for the Origins of Cognition, University of Rochester, Rochester, NY, USA.
Anim Cogn. 2018 Sep;21(5):671-684. doi: 10.1007/s10071-018-1202-2. Epub 2018 Jul 3.
Previous studies have shown that the pupils dilate more in anticipation of larger rewards. This finding raises the possibility of a more general association between reward amount and pupil size. We tested this idea by characterizing macaque pupil responses to offered rewards during evaluation and comparison in a binary choice task. To control attention, we made use of a design in which offers occurred in sequence. By looking at pupil responses after choice but before reward, we confirmed the previously observed positive association between pupil size and anticipated reward values. Surprisingly, however, we find that pupil size is negatively correlated with the value of offered gambles before choice, during both evaluation and comparison stages of the task. These results demonstrate a functional distinction between offered and anticipated rewards and present evidence against a narrow version of the simulation hypothesis; the idea that we represent offers by reactivating states associated with anticipating them. They also suggest that pupil size is correlated with relative, not absolute, values of offers, suggestive of an accept-reject model of comparison.
先前的研究表明，在预期获得更大奖励时，瞳孔会扩张得更明显。这一发现增加了奖励金额与瞳孔大小之间存在更普遍关联的可能性。我们通过在二元选择任务的评估和比较过程中，刻画猕猴对所提供奖励的瞳孔反应，来验证这一想法。为了控制注意力，我们采用了一种奖励依次出现的设计。通过观察选择后但奖励前的瞳孔反应，我们证实了之前观察到的瞳孔大小与预期奖励值之间的正相关关系。然而，令人惊讶的是，我们发现，在任务的评估和比较阶段，选择前提供的赌博价值与瞳孔大小呈负相关。这些结果表明了所提供奖励与预期奖励之间的功能差异，并提供了证据反驳模拟假设的狭义版本；即我们通过重新激活与预期奖励相关的状态来表征所提供的奖励这一观点。它们还表明，瞳孔大小与所提供奖励的相对价值而非绝对价值相关，这暗示了一种接受-拒绝比较模型。
