Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Australia.
Melbourne School of Psychological Sciences, The University of Melbourne, Melbourne, Australia.
Neuroimage. 2021 Sep;238:118265. doi: 10.1016/j.neuroimage.2021.118265. Epub 2021 Jun 17.
How we exert control over our decision-making has been investigated using conflict tasks, which involve stimuli containing elements that are either congruent or incongruent. In these tasks, participants adapt their decision-making strategies following exposure to incongruent stimuli. According to conflict monitoring accounts, conflicting stimulus features are detected in medial frontal cortex, and the extent of experienced conflict scales with response time (RT) and frontal theta-band activity in the Electroencephalogram (EEG). However, the consequent adjustments to decision processes following response conflict are not well-specified. To characterise these adjustments and their neural implementation we recorded EEG during a modified Flanker task. We traced the time-courses of performance monitoring processes (frontal theta) and multiple processes related to perceptual decision-making. In each trial participants judged which of two overlaid gratings forming a plaid stimulus (termed the S1 target) was of higher contrast. The stimulus was divided into two sections, which each contained higher contrast gratings in either congruent or incongruent directions. Shortly after responding to the S1 target, an additional S2 target was presented, which was always congruent. Our EEG results suggest enhanced sensory evidence representations in visual cortex and reduced evidence accumulation rates for S2 targets following incongruent S1 stimuli. Results of a follow-up behavioural experiment indicated that the accumulation of sensory evidence from the incongruent (i.e. distracting) stimulus element was adjusted following response conflict. Frontal theta amplitudes positively correlated with RT following S1 targets (in line with conflict monitoring accounts). Following S2 targets there was no such correlation, and theta amplitude profiles instead resembled decision evidence accumulation trajectories. Our findings provide novel insights into how cognitive control is implemented following exposure to conflicting information, which is critical for extending conflict monitoring accounts.
我们使用包含一致或不一致元素的冲突任务来研究我们如何控制自己的决策。在这些任务中，参与者在暴露于不一致的刺激后会调整他们的决策策略。根据冲突监测理论，在中额叶皮层中检测到冲突的刺激特征，并且所经历的冲突程度与反应时（RT）和脑电图（EEG）中的额部θ波段活动成正比。然而，对响应冲突后决策过程的后续调整并没有很好地说明。为了描述这些调整及其神经实现，我们在修改后的 Flanker 任务中记录了 EEG。我们追踪了绩效监测过程（额部θ波）和与知觉决策相关的多个过程的时间过程。在每次试验中，参与者判断两个重叠的光栅（称为 S1 目标）中哪一个对比度更高，这些光栅形成了一个格子刺激。刺激被分为两部分，每个部分都包含在一致或不一致方向上具有更高对比度的光栅。在对 S1 目标做出反应后不久，会呈现一个附加的 S2 目标，它总是一致的。我们的 EEG 结果表明，在视觉皮层中，对不一致（即分散注意力）刺激元素的感觉证据表示增强，并且在 S1 刺激不一致的情况下，S2 目标的证据积累速度降低。后续行为实验的结果表明，在响应冲突后，从不一致（即分散注意力）刺激元素中积累的感觉证据被调整了。在 S1 目标之后，额部θ波幅度与 RT 呈正相关（与冲突监测理论一致）。在 S2 目标之后，没有这样的相关性，并且θ波幅度曲线类似于决策证据积累轨迹。我们的发现为冲突监测理论提供了新的见解，即如何在暴露于冲突信息后实施认知控制，这对于扩展冲突监测理论至关重要。
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