Astle D E, Jackson G M, Swainson R
Department of Experimental Psychology, University of Oxford, Oxford, UK.
Eur J Neurosci. 2008 Oct;28(7):1404-18. doi: 10.1111/j.1460-9568.2008.06439.x.
Task-switching has proved to be a fruitful paradigm for studying cognitive control mechanisms. Interestingly, this avenue of study has revealed that subjects are, to some degree, able to bring about a change in task-set prior to the performance of that task (provided that they are given advance warning of the upcoming task, for instance in the form of a cue). Event-related potentials (ERPs) have proved to be a good way of measuring these rapid anticipatory control processes. To explore these processes further, the current study examined the relationship between the availability of spatial information and cue-locked task-switching ERP effects. Two groups of subjects were compared: one group could separate the task-sets on the basis of the targets' colour (the 'colour' group), the second on the basis of the targets' location (the 'spatial' group). The performance of both groups benefited to the same extent from advance cueing of task-transitions (switches or repeats), yet the ERP data revealed cue-locked (but not target-locked) differences between the two groups. The most striking of these differences was the absence of both a late positivity over posterior scalp and a late negativity over frontal scalp when the spatial group switched between tasks. Thus, it seems unlikely that these effects index stimulus-response 'reconfiguration'per se--as the mappings were identical for both groups of subjects--but rather that these task-switching processes are sensitive to how the mappings are represented.
事实证明，任务切换是研究认知控制机制的一种富有成效的范式。有趣的是，这一研究途径表明，受试者在执行任务之前，在某种程度上能够改变任务集（前提是他们得到即将执行任务的提前警告，例如以提示的形式）。事件相关电位（ERP）已被证明是测量这些快速预期控制过程的好方法。为了进一步探索这些过程，本研究考察了空间信息的可用性与提示锁定任务切换ERP效应之间的关系。比较了两组受试者：一组可以根据目标颜色区分任务集（“颜色”组），另一组根据目标位置区分任务集（“空间”组）。两组受试者的表现都在相同程度上受益于任务转换（切换或重复）的提前提示，但ERP数据显示两组之间存在提示锁定（而非目标锁定）差异。这些差异中最显著的是，当空间组在任务之间切换时，后头皮没有出现晚期正电位，前头皮也没有出现晚期负电位。因此，这些效应似乎不太可能本身就指示刺激-反应“重新配置”——因为两组受试者的映射是相同的——而是这些任务切换过程对映射的表示方式很敏感。
