任务转换条件下对特征的并行搜索

采用双任务范式，以两个实验探讨了任务设置与刺激特征的匹配程度对特征搜索方式的影响。要求被试首先辨认数字序列中包含的字母，随后完成特征搜索任务。在实验一中特征搜索任务是检测同时呈现的多个灰色圆点(干扰子）中是否有红色圆点(目标）出现。在实验二中，以多种不同颜色的圆点代替实验一中的灰色干扰子。结果发现：在特征搜索主要由自下而上的信息或自上而下的信息引导的两种条件下，任务设置与刺激特征的匹配程度均不影响特征搜索方式，特征搜索仍以并行方式进行。据上述结果笔者推测，在任务设置与刺激特征不匹配的条件下，视觉加工系统首先调整任务设置使二者相匹配，随后进行高效率的并行搜索，而非在二者不匹配的条件下进行低效率的系列搜索。

FEATURE SEARCH WAS STILL PARALLEL UNDER TASK-SWITCH CONDITION

With two experiments, using the dual-task paradigm, this paper discussed the influence of matching degree of task-set and stimuli's property towards the pattern of feature search. Participants were required to identify the unique letter in the stream of Arabic numerals (T1), and then completed a feature search task (T2). In experiment 1, T2 was to detect a red dot among grey distractors. In experiment 2, grey distractors were replayed by multiple colored dots. The results reveal that the pattern of feature search cannot be influenced by the matching degree of task-set and stimuli's property, no matter the feature search is primarily guided by bottom-up information or top-down information. According to these results, it is suggested that detection of a specific feature is executed in a parallel pattern with high efficiency after task-switch is completed, rather then in a serial pattern with low efficiency while task-switch was uncompleted.