Department of Psychology, Vanderbilt Vision Research Center, Center for Cognitive and Integrative Cognitive Neuroscience, Vanderbilt University, Nashville, Tennessee 37240-7817, USA.
J Neurosci. 2011 Sep 21;31(38):13535-45. doi: 10.1523/JNEUROSCI.1691-11.2011.
It has been intensely debated whether visual stimuli are processed to the point of semantic analysis in the absence of awareness. In the present study, we measured the extent to which the meaning of a stimulus was registered using the N400 component of human event-related potentials (ERPs), a highly sensitive index of the semantic mismatch between a stimulus and the context in which it is presented. Observers judged the semantic relatedness of a context and target word while ERPs were recorded under continuous flash suppression (Experiments 1 and 2) and binocular rivalry (Experiment 3). Finally, we parametrically manipulated the visibility of the target word by increasing the contrast between the target word and the suppressive stimulus presented to the other eye (Experiment 4). We found that the amplitude of the N400 was attenuated with increasing suppression depth and was absent whenever the observers could not discriminate the meaning of suppressed words. We discuss these findings in the context of single-process models of consciousness, which can account for a large body of empirical evidence obtained from visual masking, attentional manipulations, and, now, interocular suppression paradigms.
是否在无意识的情况下，视觉刺激也能被处理到语义分析的程度，这一直是激烈争论的问题。在本研究中，我们使用人类事件相关电位（ERP）的 N400 成分来衡量刺激的意义被记录的程度，N400 是刺激与其呈现的上下文之间语义不匹配的高度敏感指标。在连续闪光抑制（实验 1 和 2）和双眼竞争（实验 3）下，观察者判断上下文和目标词的语义相关性，同时记录 ERP。最后，我们通过增加目标词与呈现给另一只眼睛的抑制性刺激之间的对比度来参数化地操纵目标词的可见度（实验 4）。我们发现，随着抑制深度的增加，N400 的振幅减弱，并且只要观察者无法区分被抑制词的含义，N400 就会消失。我们在意识的单过程模型的背景下讨论这些发现，这些模型可以解释从视觉掩蔽、注意力操作以及现在的眼间抑制范式中获得的大量经验证据。
