Vogel Edward K, Woodman Geoffrey F, Luck Steven J
Department of Psychology, University of Oregon, Eugene, 97403-1227, USA.
J Cogn Neurosci. 2005 Dec;17(12):1907-22. doi: 10.1162/089892905775008599.
Attention operates at an early stage in some experimental paradigms and at a late stage in others, which suggests that the locus of selection is flexible. The present study was designed to determine whether the locus of selection can vary flexibly within a single experimental paradigm as a function of relatively modest variations in stimulus and task parameters. In the first experiment, a new method for assessing the locus of selection was developed. Specifically, attention can influence perceptual encoding only if it is directed to the target before a perceptual representation of the target has been formed, whereas attention can influence postperceptual processes even if attention is cued after perception is complete. Event-related potentials were used to confirm the validity of this method. The subsequent experiments used cueing tasks in which subjects were required to perceive and remember a set of objects, and the difficulty of the perception and memory components of the task were varied. When the task overloaded perception but not working memory, attention influenced the formation of perceptual representations but not the storage of these representations in memory; when the task overloaded working memory but not perception, attention influenced the transfer of perceptual representations into memory but not the formation of the perceptual representations. Thus, attention operates to select relevant information at whatever stage or stages of processing are overloaded by a particular stimulus-task combination.
在某些实验范式中，注意在早期阶段起作用，而在其他范式中则在后期阶段起作用，这表明选择位点是灵活的。本研究旨在确定在单一实验范式中，选择位点是否会随着刺激和任务参数的相对适度变化而灵活变化。在第一个实验中，开发了一种评估选择位点的新方法。具体而言，只有当注意在目标的知觉表征形成之前指向目标时，注意才能影响知觉编码，而即使在知觉完成后提示注意，注意也能影响知觉后加工过程。事件相关电位被用来证实这种方法的有效性。随后的实验使用了提示任务，要求受试者感知并记住一组物体，并且任务中感知和记忆成分的难度是变化的。当任务使感知过载但不使工作记忆过载时，注意影响知觉表征的形成，但不影响这些表征在记忆中的存储；当任务使工作记忆过载但不使感知过载时，注意影响知觉表征向记忆的转移，但不影响知觉表征的形成。因此，对于特定刺激-任务组合使加工的任何一个或多个阶段过载的情况，注意都会起作用来选择相关信息。
