The role of spatial information in advance task-set control: an event-related potential study.

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.