Discipline of Psychology, College of Science, Health, Engineering and Education, Murdoch University, Perth, Australia.
Department of Psychiatry and Human Behavior, School of Medicine, University of California, Irvine, United States of America.
PLoS Biol. 2023 Jun 20;21(6):e3001866. doi: 10.1371/journal.pbio.3001866. eCollection 2023 Jun.
Prediction error is a basic component of predictive-coding theory of brain processing. According to the theory, each stage of brain processing of sensory information generates a model of the current sensory input; subsequent input is compared against the model and only if there is a mismatch, a prediction error, is further processing performed. Recently, Smout and colleagues found that a signature of prediction error, the visual (v) mismatch negativity (MMN), for a fundamental property of visual input-its orientation-was absent without endogenous attention on the stimuli. This is remarkable because the weight of evidence for MMNs from audition and vision is that they occur without endogenous attention. To resolve this discrepancy, we conducted an experiment addressing 2 alternative explanations for Smout and colleagues' finding: that it was from a lack of reproducibility or that participants' visual systems did not encode the stimuli when attention was on something else. We conducted a similar experiment to that of Smout and colleagues. We showed 21 participants sequences of identically oriented Gabor patches, standards, and, unpredictably, otherwise identical, Gabor patches differing in orientation by ±15°, ±30°, and ±60°, deviants. To test whether participants encoded the orientation of the standards, we varied the number of standards preceding a deviant, allowing us to search for a decrease in activity with the number of repetitions of standards-repetition suppression. We diverted participants' attention from the oriented stimuli with a central, letter-detection task. We reproduced Smout and colleagues' finding of no vMMN without endogenous attention, strengthening their finding. We found that our participants showed repetition suppression: They did encode the stimuli preattentively. We also found early processing of deviants. We discuss various explanations why the earlier processing did not extend into the vMMN time window, including low precision of prediction.
预测误差是大脑处理的预测编码理论的基本组成部分。根据该理论，大脑对感觉信息的每个处理阶段都会生成当前感觉输入的模型；随后将输入与模型进行比较，只有在不匹配的情况下，即出现预测误差时，才会进行进一步的处理。最近，Smout 及其同事发现，一种预测误差的特征，即视觉（v）失匹配负波（MMN），对于视觉输入的一个基本属性——其方向——在刺激物上没有内源性注意时不存在。这是非常值得注意的，因为来自听觉和视觉的 MMN 的证据权重表明它们在没有内源性注意的情况下发生。为了解决这一差异，我们进行了一项实验，以解决 Smout 及其同事的发现的两种替代解释：要么是由于缺乏可重复性，要么是当注意力集中在其他事物上时，参与者的视觉系统没有对刺激进行编码。我们进行了与 Smout 及其同事类似的实验。我们向 21 名参与者展示了一系列相同方向的 Gabor 补丁、标准，以及不可预测的、方向略有不同的、相同的 Gabor 补丁，方向相差 ±15°、±30°和 ±60°，为偏差。为了测试参与者是否编码了标准的方向，我们改变了一个偏差之前的标准数量，允许我们搜索随着标准重复次数的减少，活动的减少——重复抑制。我们用中央的字母检测任务将参与者的注意力从定向刺激上转移开。我们重现了 Smout 及其同事在没有内源性注意的情况下没有 vMMN 的发现，加强了他们的发现。我们发现我们的参与者表现出重复抑制：他们确实在无意识地编码刺激。我们还发现了对偏差的早期处理。我们讨论了各种解释，包括预测精度低，为什么早期处理没有扩展到 vMMN 时间窗口。
