Chen Yuanyuan, Davis Matthew H, Pulvermüller Friedemann, Hauk Olaf
Neuroscience and Aphasia Research Unit, Manchester, UK.
MRC Cognition and Brain Sciences Unit, Cambridge, UK.
J Cogn Neurosci. 2015 Sep;27(9):1738-51. doi: 10.1162/jocn_a_00815. Epub 2015 Apr 7.
Visual word recognition is often described as automatic, but the functional locus of top-down effects is still a matter of debate. Do task demands modulate how information is retrieved, or only how it is used? We used EEG/MEG recordings to assess whether, when, and how task contexts modify early retrieval of specific psycholinguistic information in occipitotemporal cortex, an area likely to contribute to early stages of visual word processing. Using a parametric approach, we analyzed the spatiotemporal response patterns of occipitotemporal cortex for orthographic, lexical, and semantic variables in three psycholinguistic tasks: silent reading, lexical decision, and semantic decision. Task modulation of word frequency and imageability effects occurred simultaneously in ventral occipitotemporal regions-in the vicinity of the putative visual word form area-around 160 msec, following task effects on orthographic typicality around 100 msec. Frequency and typicality also produced task-independent effects in anterior temporal lobe regions after 200 msec. The early task modulation for several specific psycholinguistic variables indicates that occipitotemporal areas integrate perceptual input with prior knowledge in a task-dependent manner. Still, later task-independent effects in anterior temporal lobes suggest that word recognition eventually leads to retrieval of semantic information irrespective of task demands. We conclude that even a highly overlearned visual task like word recognition should be described as flexible rather than automatic.
视觉单词识别通常被描述为自动的，但自上而下效应的功能位点仍是一个有争议的问题。任务要求是调节信息的检索方式，还是仅调节信息的使用方式？我们使用脑电图/脑磁图记录来评估任务背景是否、何时以及如何改变枕颞叶皮质中特定心理语言学信息的早期检索，枕颞叶皮质这一区域可能对视觉单词处理的早期阶段有贡献。我们采用参数化方法，分析了枕颞叶皮质在默读、词汇判断和语义判断这三项心理语言学任务中，针对正字法、词汇和语义变量的时空反应模式。在大约100毫秒时任务对正字法典型性产生影响之后，大约160毫秒时，单词频率和可意象性效应的任务调节在腹侧枕颞叶区域——假定的视觉单词形式区域附近——同时出现。200毫秒后，频率和典型性在前颞叶区域也产生了与任务无关的效应。对几个特定心理语言学变量的早期任务调节表明，枕颞叶区域以任务依赖的方式将感知输入与先验知识整合起来。尽管如此，前颞叶后期与任务无关的效应表明，单词识别最终会导致语义信息的检索，而与任务要求无关。我们得出结论，即使是像单词识别这样高度过度学习的视觉任务，也应被描述为灵活的而非自动的。
