Maniscalco Brian, McCurdy Li Yan, Odegaard Brian, Lau Hakwan
Neuroscience Institute, New York University, New York, New York 10016,
Department of Psychology, Columbia University, New York, New York 10027.
J Neurosci. 2017 Feb 1;37(5):1213-1224. doi: 10.1523/JNEUROSCI.2271-13.2016. Epub 2016 Dec 27.
Why do experimenters give subjects short breaks in long behavioral experiments? Whereas previous studies suggest it is difficult to maintain attention and vigilance over long periods of time, it is unclear precisely what mechanisms benefit from rest after short experimental blocks. Here, we evaluate decline in both perceptual performance and metacognitive sensitivity (i.e., how well confidence ratings track perceptual decision accuracy) over time and investigate whether characteristics of prefrontal cortical areas correlate with these measures. Whereas a single-process signal detection model predicts that these two forms of fatigue should be strongly positively correlated, a dual-process model predicts that rates of decline may dissociate. Here, we show that these measures consistently exhibited negative or near-zero correlations, as if engaged in a trade-off relationship, suggesting that different mechanisms contribute to perceptual and metacognitive decisions. Despite this dissociation, the two mechanisms likely depend on common resources, which could explain their trade-off relationship. Based on structural MRI brain images of individual human subjects, we assessed gray matter volume in the frontal polar area, a region that has been linked to visual metacognition. Variability of frontal polar volume correlated with individual differences in behavior, indicating the region may play a role in supplying common resources for both perceptual and metacognitive vigilance. Additional experiments revealed that reduced metacognitive demand led to superior perceptual vigilance, providing further support for this hypothesis. Overall, results indicate that during breaks between short blocks, it is the higher-level perceptual decision mechanisms, rather than lower-level sensory machinery, that benefit most from rest.
Perceptual task performance declines over time (the so-called vigilance decrement), but the relationship between vigilance in perception and metacognition has not yet been explored in depth. Here, we show that patterns in perceptual and metacognitive vigilance do not follow the pattern predicted by a previously suggested single-process model of perceptual and metacognitive decision making. We account for these findings by showing that regions of anterior prefrontal cortex (aPFC) previously associated with visual metacognition are also associated with perceptual vigilance. We also show that relieving metacognitive task demand improves perceptual vigilance, suggesting that aPFC may house a limited cognitive resource that contributes to both metacognition and perceptual vigilance. These findings advance our understanding of the mechanisms and dynamics of perceptual metacognition.
在长时间的行为实验中，为什么实验者要让受试者短暂休息？尽管先前的研究表明长时间保持注意力和警觉性很困难，但尚不清楚在短暂的实验阶段后，究竟是什么机制从休息中受益。在这里，我们评估了随着时间推移感知性能和元认知敏感性（即信心评级跟踪感知决策准确性的程度）的下降情况，并研究前额叶皮层区域的特征是否与这些指标相关。虽然单过程信号检测模型预测这两种疲劳形式应该呈强正相关，但双过程模型预测下降速率可能会分离。在这里，我们表明这些指标始终呈现负相关或接近零的相关性，就好像处于一种权衡关系中，这表明不同的机制对感知和元认知决策有贡献。尽管存在这种分离，但这两种机制可能依赖于共同的资源，这可以解释它们的权衡关系。基于个体人类受试者的结构磁共振成像脑图像，我们评估了额极区的灰质体积，该区域与视觉元认知有关。额极体积的变异性与行为上的个体差异相关，表明该区域可能在为感知和元认知警觉提供共同资源方面发挥作用。额外的实验表明，降低元认知需求会导致更好的感知警觉，为这一假设提供了进一步的支持。总体而言，结果表明在短阶段之间的休息期间，受益于休息最多的是较高层次的感知决策机制，而不是较低层次的感觉机制。
感知任务表现会随着时间下降（即所谓的警觉性递减），但感知警觉性和元认知之间的关系尚未得到深入探讨。在这里，我们表明感知和元认知警觉的模式并不遵循先前提出的感知和元认知决策单过程模型所预测的模式。我们通过表明先前与视觉元认知相关的前额叶前皮层（aPFC）区域也与感知警觉相关来解释这些发现。我们还表明减轻元认知任务需求会提高感知警觉，这表明aPFC可能容纳一种有限的认知资源，该资源对元认知和感知警觉都有贡献。这些发现推进了我们对感知元认知机制和动态的理解。
