Université Laval, Canada.
J Cogn Neurosci. 2012 Mar;24(3):611-26. doi: 10.1162/jocn_a_00149. Epub 2011 Oct 7.
There is growing evidence that processes formerly believed to be automatic are, in fact, strongly modulated by top-down influences. The purpose of the present work was to investigate how cognitive control can affect the purported automaticity of word processing by examining the impact of task switching on semantic processing using the ERP technique. In the context of the psychological refractory period dual-task paradigm, two experiments contrasted the context-sensitive N400 ERP elicited by the second of two target words under conditions that involved either a task switch or no-task switch. Although the N400 was not affected by SOA in the absence of switching, it was strongly attenuated at short SOAs when the psychological refractory period procedure involved a switch from a perceptual to a semantic task (Experiment 1) or a switch between two different semantic tasks (Experiment 2). These findings suggest that semantic processing cannot be performed in parallel with task switching and illustrate limitations in the ability of the cognitive system to adapt flexibly to the dynamically changing challenges of the environment according to task demands and behavioral goals.
越来越多的证据表明，以前被认为是自动的过程实际上受到自上而下的影响的强烈调节。本研究的目的是通过使用 ERP 技术检查任务转换对语义处理的影响，来研究认知控制如何影响据称的单词处理的自动性。在心理不应期双任务范式的背景下，两个实验对比了在涉及任务转换或无任务转换的条件下，两个目标词中的第二个词引起的语境敏感的 N400 ERP。尽管在没有转换的情况下，N400 不受 SOA 的影响，但当心理不应期过程涉及从知觉任务到语义任务的转换（实验 1）或在两个不同的语义任务之间的转换（实验 2）时，在短 SOA 时，N400 会强烈衰减。这些发现表明，语义处理不能与任务转换并行进行，并说明了认知系统根据任务需求和行为目标灵活适应环境动态变化挑战的能力的局限性。
