Department of Psychology, University of California, Santa Cruz, USA.
Department of Neurology, New York University School of Medicine, USA.
Conscious Cogn. 2022 Jul;102:103337. doi: 10.1016/j.concog.2022.103337. Epub 2022 May 4.
Near-threshold perception is a paradigm case of awareness diverging from reality - the perception of an unchanging stimulus can vacillate from undetected to clearly perceived. The amplitude of low-frequency brain oscillations - particularly in the alpha-band (8-13 Hz) - has emerged as a reliable predictor of trial-to-trial variability in perceptual decisions based on simple, low-level stimuli. Here, we addressed the question of how spontaneous oscillatory amplitude impacts subjective and objective aspects of perception using high-level visual stimuli. Human observers completed a near-threshold face/house discrimination task with subjective visibility ratings while electroencephalograms (EEG) were recorded. Using single-trial multiple regression analysis, we found that spontaneous fluctuations in prestimulus alpha-band amplitude were negatively related to visibility judgments but did not predict trial-by-trial accuracy. These results extend previous findings that indicate that strong prestimulus alpha diminishes subjective perception without affecting the accuracy or sensitivity (d') of perceptual decisions into the domain of high-level perception.
阈下感知是意识与现实背离的典型范例——对不变刺激的感知可以从未检测到到清晰感知之间摇摆不定。低频脑振荡的幅度——特别是在 alpha 波段（8-13 Hz）——已成为基于简单、低水平刺激的感知决策中试次间可变性的可靠预测指标。在这里，我们使用高级视觉刺激来解决自发振荡幅度如何影响主观和客观感知的问题。人类观察者在进行脑电图 (EEG) 记录的同时，完成了阈下人脸/房屋辨别任务，并进行了主观可见度评分。使用单次试验多元回归分析，我们发现，刺激前 alpha 波段振幅的自发波动与可见度判断呈负相关，但不能预测试次间的准确性。这些结果扩展了先前的发现，即强烈的刺激前 alpha 减弱主观感知而不影响感知决策的准确性或敏感性 (d')，进入高级感知领域。
