Abstract: This research focused on the pattern (serial or parallel) of visual search under the condition of dual-task with stimuli presented in RSVP stream. Participants were required to identify the unique letter in the stream of Arabic numerals (T1), and then completed a feature search task (T2). In exp1, T2 was to detect an odd-oriented ellipse among distractors which were tilted in the same direction. In exp2, T2 was to detect a red dot among grey distractors. Two experiments provided convergent evidence that the accuracy of T2 was progressively decreased as T1-T2 lag was shortened; the increase of distractors’ set size didn’t result in a deficit for the feature search task. The results showed that although the efficiency of T2 had been impaired by task-switch, feature search was still processed in a parallel pattern. However, according to dynamic control theory, the involvement of task-switch in this research should change the pattern of feature search from parallel to serial. The potential solutions for the inconsistency between dynamic control theory and the current results were discussed in detail.

Key words: feature search, dynamic control theory, task switch, attention blink