Schurger Aaron, Kim Min-Soo, Cohen Jonathan D
Department of Psychology, Princeton University, Princeton, New Jersey, United States of America; Princeton Neuroscience Institute, Princeton University, Princeton, New Jersey, United States of America; INSERM U992 / NeuroSpin, CEA-Saclay, Gif-sur-Yvette cedex, France.
Department of Psychology, Princeton University, Princeton, New Jersey, United States of America.
PLoS One. 2015 May 8;10(5):e0125278. doi: 10.1371/journal.pone.0125278. eCollection 2015.
In humans and some other species perceptual decision-making is complemented by the ability to make confidence judgements about the certainty of sensory evidence. While both forms of decision process have been studied empirically, the precise relationship between them remains poorly understood. We performed an experiment that combined a perceptual decision-making task (identifying the category of a faint visual stimulus) with a confidence-judgement task (wagering on the accuracy of each perceptual decision). The visual stimulation paradigm required steady fixation, so we used eye-tracking to control for stray eye movements. Our data analyses revealed an unexpected and counterintuitive interaction between the steadiness of fixation (prior to and during stimulation), perceptual decision making, and post-decision wagering: greater variability in gaze direction during fixation was associated with significantly increased visual-perceptual sensitivity, but significantly decreased reliability of confidence judgements. The latter effect could not be explained by a simple change in overall confidence (i.e. a criterion artifact), but rather was tied to a change in the degree to which high wagers predicted correct decisions (i.e. the sensitivity of the confidence judgement). We found no evidence of a differential change in pupil diameter that could account for the effect and thus our results are consistent with fixational eye movements being the relevant covariate. However, we note that small changes in pupil diameter can sometimes cause artefactual fluctuations in measured gaze direction and this possibility could not be fully ruled out. In either case, our results suggest that perceptual decisions and confidence judgements can be processed independently and point toward a new avenue of research into the relationship between them.
在人类和其他一些物种中，感知决策通过对感官证据的确定性做出置信度判断的能力得到补充。虽然这两种决策过程都已通过实证研究进行了探讨，但它们之间的确切关系仍知之甚少。我们进行了一项实验，将感知决策任务（识别微弱视觉刺激的类别）与置信度判断任务（对每个感知决策的准确性进行投注）相结合。视觉刺激范式要求稳定注视，因此我们使用眼动追踪来控制眼球的随意运动。我们的数据分析揭示了注视稳定性（刺激前和刺激期间）、感知决策和决策后投注之间存在一种意想不到且违反直觉的相互作用：注视期间注视方向的更大变异性与视觉感知敏感性显著增加相关，但置信度判断的可靠性显著降低。后一种效应不能用总体置信度的简单变化（即标准假象）来解释，而是与高投注预测正确决策的程度变化（即置信度判断的敏感性）有关。我们没有发现瞳孔直径的差异变化可以解释这种效应的证据，因此我们的结果与注视性眼动是相关协变量一致。然而，我们注意到瞳孔直径的微小变化有时会导致测量的注视方向出现人为波动，这种可能性无法完全排除。无论哪种情况，我们的结果都表明感知决策和置信度判断可以独立处理，并指向了它们之间关系研究的一个新途径。
