Hoffmeister Jennifer-Ashley, Smit Andrea N, Livingstone Ashley C, McDonald John J
Simon Fraser University, Burnaby, British Columbia, Canada.
J Cogn Neurosci. 2022 Jan 5;34(2):348-364. doi: 10.1162/jocn_a_01797.
The control processes that guide attention to a visual-search target can result in the selection of an irrelevant object with similar features (a distractor). Once attention is captured by such a distractor, search for a subsequent target is momentarily impaired if the two stimuli appear at different locations. The textbook explanation for this impairment is based on the notion of an indivisible focus of attention that moves to the distractor, illuminates a nontarget that subsequently appears at that location, and then moves to the target once the nontarget is rejected. Here, we show that such delayed orienting to the target does not underlie the behavioral cost of distraction. Observers identified a color-defined target appearing within the second of two stimulus arrays. The first array contained irrelevant items, including one that shared the target's color. ERPs were examined to test two predictions stemming from the textbook serial-orienting hypothesis. Namely, when the target and distractor appear at different locations, (1) the target should elicit delayed selection activity relative to same-location trials, and (2) the nontarget search item appearing at the distractor location should elicit selection activity that precedes selection activity tied to the target. Here, the posterior contralateral N2 component was used to track selection of each of these search-array items and the previous distractor. The results supported neither prediction above, thereby disconfirming the serial-orienting hypothesis. Overall, the results show that the behavioral costs of distraction are caused by perceptual and postperceptual competition between concurrently attended target and nontarget stimuli.
引导注意力至视觉搜索目标的控制过程可能会导致选择一个具有相似特征的无关物体（干扰项）。一旦注意力被这样一个干扰项捕获，如果两个刺激出现在不同位置，那么对后续目标的搜索会暂时受到损害。对此种损害的教科书式解释基于注意力不可分割的焦点这一概念，该焦点移向干扰项，照亮随后出现在该位置的非目标物体，然后在非目标物体被排除后移向目标。在此，我们表明，这种对目标的延迟定向并非分心行为代价的基础。观察者识别出出现在两个刺激阵列中第二个阵列内的颜色定义目标。第一个阵列包含无关项目，其中一个与目标颜色相同。我们检查了事件相关电位（ERPs），以检验源于教科书式序列定向假设的两个预测。具体而言，当目标和干扰项出现在不同位置时，（1）相对于同位置试验，目标应引发延迟的选择活动，并且（2）出现在干扰项位置的非目标搜索项目应引发先于与目标相关的选择活动的选择活动。在此，对侧后N2成分被用于追踪这些搜索阵列项目以及先前干扰项中每一个的选择情况。结果不支持上述任何一个预测，从而否定了序列定向假设。总体而言，结果表明分心的行为代价是由同时被关注的目标和非目标刺激之间的感知及感知后竞争所导致的。
