Leibniz Research Centre for Working Environment and Human Factors at the Technical University of Dortmund, Germany.
Cortex. 2010 Oct;46(9):1138-48. doi: 10.1016/j.cortex.2009.07.014. Epub 2009 Aug 5.
Switching among cognitive tasks results in switch costs which are only partly reduced even after sufficient task preparation. These residual switch costs are frequently explained in terms of interference of simultaneously active task representations that delays selection of a correct response. Recent studies showed that the benefit of a task- and response-set repetition can also explain residual costs. We aimed to extend the findings by clarifying the mechanisms underlying task- and response-mode repetition benefit as well as costs arising by switch of one or both dimensions. To this end we used a combination of task-switching and go/no-go paradigm during an electrophysiological recording. Particularly, we focused on the frontocentral N2, which has been usually related to conflict, but also to response selection. The behavioral results replicate previous findings of lack of residual switch costs due to slower responses in task repetitions (TRs) following no-go relative to go trials. This indicates elimination of TR benefit when in a previous trial no response was selected and prepared. In other words, task sets clearly benefits from repetition of response mode whereas interference seems to occur whenever the task-set, the response mode or both were switched. Trial incongruity increased reaction times. The event-related potentials (ERPs) revealed a frontocentral N2 in all conditions which followed the same pattern as the reaction times (RTs), showing smaller amplitude and peaking earlier when both the task and response mode were repeated relative to the three switching conditions. Similar to the behavioral data, the N2 increased as a function of incongruity. Finally, both the N2 amplitude and latency correspond closely to the residual switch costs. This finding suggests that task-set or response mode switching intensify and delay response selection, relative to the repetition of both dimensions.
在认知任务之间切换会导致切换代价，即使进行了充分的任务准备，这些代价也只能部分降低。这些残余的切换代价通常可以用同时激活的任务表示的干扰来解释，这种干扰会延迟正确反应的选择。最近的研究表明，任务和反应集重复的益处也可以解释残余的代价。我们的目的是通过阐明任务和反应模式重复的好处以及由于一个或两个维度的切换而产生的代价的机制来扩展这些发现。为此，我们在电生理记录期间使用了任务切换和 Go/No-Go 范式的组合。特别是，我们专注于额中央 N2，它通常与冲突有关，但也与反应选择有关。行为结果复制了先前的发现，即由于在 Go 试验之后的 No-Go 试验中反应较慢，因此不存在残余的切换代价。这表明，当在前一个试验中没有选择和准备反应时，TR 益处会被消除。换句话说，任务集明显受益于反应模式的重复，而干扰似乎发生在任务集、反应模式或两者都切换时。试验不一致性增加了反应时间。事件相关电位 (ERP) 显示了额中央 N2，它在所有条件下都遵循与反应时间 (RT) 相同的模式，当任务和反应模式都重复时，与三种切换条件相比，N2 的振幅较小，峰值较早。与行为数据相似，N2 随着不一致性的增加而增加。最后，N2 的振幅和潜伏期与残余的切换代价密切相关。这一发现表明，与两个维度的重复相比，任务集或反应模式的切换会加剧并延迟反应选择。
