Hsieh Shulan, Yu Yen-Ting
Department of Psychology, National Chung Cheng University, 160 San-Hsing, Ming-Hsiung, Chia-Yi 621, Taiwan.
Brain Res Brain Res Protoc. 2003 Aug;12(1):49-59. doi: 10.1016/s1385-299x(03)00071-0.
We describe a protocol to examine various hypothetical models of task switching. This protocol analyzes two event-related potentials--lateralized readiness potential (LRP) and P300--to infer the roles of advance reconfiguration and carry-over effect on task switching. Participants performed two tasks in a random order. On each trial a task from the previous trial would be repeated, or the other task would be carried out. In one scenario, each stimulus was preceded either by an informative cue specifying which of the two tasks to perform (task-cueing conditions) or by a non-informative cue (no task-cueing conditions). The results showed that the mean reaction time and the stimulus-locked LRP intervals were longer for switch than for repeated trials. This suggested that task switching affected stage processes such as stimulus identification and response selection that occur before the onset of LRP. A further analysis of P300 confined the phenomenon of task switching to the processes that occur after the stimulus identification stage. Moreover, the results of additivity between task cueing and task switching suggested that the two factors affected a distinct stage of processing. A further implication would be that there was no switch-specific control process supporting the view of carry-over effect of switch cost.
我们描述了一种用于检验任务切换各种假设模型的方案。该方案分析两种事件相关电位——偏侧化准备电位（LRP）和P300——以推断提前重新配置和延续效应在任务切换中的作用。参与者以随机顺序执行两项任务。在每次试验中，前一次试验的任务可能会被重复，或者执行另一项任务。在一种情境中，每个刺激之前要么是一个指示要执行两项任务中的哪一项的信息性线索（任务提示条件），要么是一个非信息性线索（无任务提示条件）。结果表明，与重复试验相比，切换试验的平均反应时间和刺激锁定的LRP间隔更长。这表明任务切换影响了诸如刺激识别和反应选择等在LRP开始之前发生的阶段过程。对P300的进一步分析将任务切换现象局限于刺激识别阶段之后发生的过程。此外，任务提示和任务切换之间的相加性结果表明这两个因素影响了不同的加工阶段。进一步的一个推论是，不存在支持切换成本延续效应观点的特定于切换的控制过程。
