Nako Rebecca, Wu Rachel, Eimer Martin
Department of Psychological Sciences, Birkbeck, University of London.
Department of Brain and Cognitive Sciences, University of Rochester.
J Exp Psychol Hum Percept Perform. 2014 Feb;40(1):50-60. doi: 10.1037/a0033228. Epub 2013 Jun 24.
Visual search is often controlled by attentional templates that represent specific target items or target features, but can also be directed toward object categories. We studied the relationship between item-based and category-guided attentional control during visual search for one specific item (e.g., the letter C), two or three items (e.g., the letters C, F, and X), or categorically defined targets (e.g., any letter). To assess the efficiency of visual search for single, multiple, or category-defined targets, we measured the N2pc component as an electrophysiological marker of attentional target selection. In Experiment 1, where targets were presented among distractors from a different category (e.g., letters among digits), a category-based selection strategy was available. Category-based attentional control triggered spatially selective modulations of visual-perceptual processing that emerged within less than 200 ms after stimulus onset and preceded the effects of item-specific attentional templates. In Experiment 2, where letter targets appeared among letter distractors, target detection could no longer be guided by categorical top-down task sets. Search efficiency decreased as the target set size increased, in line with capacity limitations for item-specific attentional templates. Results demonstrate that category-based attentional guidance can be used rapidly and efficiently during visual search for alphanumeric targets.
视觉搜索通常由代表特定目标项目或目标特征的注意力模板控制，但也可以指向对象类别。我们研究了在视觉搜索一个特定项目（例如字母C）、两个或三个项目（例如字母C、F和X）或按类别定义的目标（例如任何字母）过程中，基于项目的注意力控制和基于类别的注意力控制之间的关系。为了评估对单个、多个或按类别定义的目标进行视觉搜索的效率，我们测量了N2pc成分，将其作为注意力目标选择的电生理指标。在实验1中，目标呈现于来自不同类别的干扰项之中（例如数字中的字母），此时基于类别的选择策略是可行的。基于类别的注意力控制引发了视觉感知处理的空间选择性调制，这种调制在刺激开始后不到200毫秒内出现，并先于特定项目注意力模板的效应。在实验2中，字母目标出现在字母干扰项之中，目标检测不再能由基于类别的自上而下任务集引导。随着目标集大小的增加，搜索效率下降，这与特定项目注意力模板的容量限制一致。结果表明，在对字母数字目标进行视觉搜索期间，基于类别的注意力引导可以快速且高效地使用。
