Jenkins Michael, Grubert Anna, Eimer Martin
Department of Psychological Sciences, Birkbeck, University of London, Malet Street, London, WC1E 7HX, UK.
Department of Psychology, Durham University, Queen's Campus, Stockton-on-Tees, TS17 6BH, UK.
Atten Percept Psychophys. 2017 Nov;79(8):2310-2326. doi: 10.3758/s13414-017-1410-x.
It is generally assumed that during search for targets defined by a feature conjunction, attention is allocated sequentially to individual objects. We tested this hypothesis by tracking the time course of attentional processing biases with the N2pc component in tasks where observers searched for two targets defined by a colour/shape conjunction. In Experiment 1, two displays presented in rapid succession (100 ms or 10 ms SOA) each contained a target and a colour-matching or shape-matching distractor on opposite sides. Target objects in both displays elicited N2pc components of similar size that overlapped in time when the SOA was 10 ms, suggesting that attention was allocated in parallel to both targets. Analogous results were found in Experiment 2, where targets and partially matching distractors were both accompanied by an object without target-matching features. Colour-matching and shape-matching distractors also elicited N2pc components, and the target N2pc was initially identical to the sum of the two distractor N2pcs, suggesting that the initial phase of attentional object selection was guided independently by feature templates for target colour and shape. Beyond 230 ms after display onset, the target N2pc became superadditive, indicating that attentional selection processes now started to be sensitive to the presence of feature conjunctions. Results show that independent attentional selection processes can be activated in parallel by two target objects in situations where these objects are defined by a feature conjunction.
一般认为，在搜索由特征联结定义的目标时，注意力是依次分配到各个物体上的。我们通过在观察者搜索由颜色/形状联结定义的两个目标的任务中，用N2pc成分追踪注意力加工偏差的时间进程来检验这一假设。在实验1中，快速连续呈现的两个显示（100毫秒或10毫秒的刺激间隔时间），每个显示在相对的两侧都包含一个目标和一个颜色匹配或形状匹配的干扰项。当刺激间隔时间为10毫秒时，两个显示中的目标物体引发了大小相似且时间上重叠的N2pc成分，这表明注意力是并行分配到两个目标上的。在实验2中也发现了类似的结果，其中目标和部分匹配的干扰项都伴随着一个没有目标匹配特征的物体。颜色匹配和形状匹配的干扰项也引发了N2pc成分，并且目标N2pc最初与两个干扰项N2pc的总和相同，这表明注意力对象选择的初始阶段是由目标颜色和形状的特征模板独立引导的。在显示开始后超过230毫秒，目标N2pc变得超加性，这表明注意力选择过程现在开始对特征联结的存在敏感。结果表明，在由特征联结定义这些物体的情况下，两个目标物体可以并行激活独立的注意力选择过程。
