Sawaki Risa, Katayama Jun'ichi
Graduate School of Education, Hokkaido University, Kita-ku, Sapporo, Japan.
J Vis. 2008 Nov 17;8(15):4.1-8. doi: 10.1167/8.15.4.
One highly controversial issue with respect to visual selective attention concerns the degree to which the top-down attentional mechanism modulates attentional allocation to bottom-up deviation. We investigated whether top-down directed attention to a stimulus feature modulates attentional allocation to task-irrelevant, bottom-up deviation. The P3 event-related potential was measured as an electrophysiological marker of attentional allocation. Target and non-target objects were serially presented in random order. Bottom-up deviations occurred as a change in task-irrelevant features of target or non-target objects, or as the appearance of task-irrelevant distractor objects around target or non-target objects. When task-irrelevant features were changed, the P3 deviant effect was greater in target than in non-target trials. In contrast, when distractor objects appeared, the P3 deviant effect was smaller in target than in non-target trials. These findings suggest that top-down directed attention to a stimulus feature modulates attentional allocation to bottom-up deviation such that attentional allocation is enhanced when bottom-up deviation and an attended feature share the same object but is inhibited when bottom-up deviation occurs outside an object with an attended feature. Thus, the top-down attentional mechanism has a strong influence even for deviant processing and provides a competitive advantage for objects with an attended feature.
关于视觉选择性注意，一个极具争议的问题涉及自上而下的注意机制对自下而上偏差的注意分配的调节程度。我们研究了对刺激特征的自上而下定向注意是否会调节对任务无关的自下而上偏差的注意分配。测量P3事件相关电位作为注意分配的电生理指标。目标和非目标物体以随机顺序依次呈现。自下而上的偏差表现为目标或非目标物体的任务无关特征的变化，或者目标或非目标物体周围出现任务无关的干扰物体。当任务无关特征发生变化时，目标试验中的P3偏差效应比非目标试验中的更大。相反，当干扰物体出现时，目标试验中的P3偏差效应比非目标试验中的更小。这些发现表明，对刺激特征的自上而下定向注意调节了对自下而上偏差的注意分配，使得当自下而上偏差和被关注特征共享同一物体时，注意分配得到增强，但当自下而上偏差出现在具有被关注特征的物体之外时则受到抑制。因此，自上而下的注意机制即使对偏差处理也有很大影响，并为具有被关注特征的物体提供竞争优势。
