A new account of the effect of probability on task switching: ERP evidence following the manipulation of switch probability, cue informativeness and predictability

► Study tested different accounts that propose to explain switch probability effects. ► Frequent task switching increases general and decreases specific switch RT costs. ► Frequent task switching is associated with increased baseline task-set activation. ► Pre-cue advance preparation appears for frequent but not infrequent switching. ► Switch probability effects can be explained by an extended activation account. This task-switching ERP study of 16 young participants investigated whether increased RT slowing on stay trials and faster RTs on switch trials for frequent than infrequent switching are explained by an activation or preparation account. The activation account proposes that task sets are maintained at a higher baseline activation level for frequent switching, necessitating increased task-set updating, as reflected by a larger and/or longer lasting early parietal positivity. The preparation account assumes advance (pre-cue) switch preparation (i.e., task-set reconfiguration), preceding stay and switch trials for frequent switching, as reflected by pre-cue and post-cue late parietal positivities. By and large, the data support the activation account. However, we also found increased, pre-cue task-set updating on frequent stay trials and pre-cue, task-set reconfiguration prior to predictable, frequent switches. These results lead us to propose an extended activation account to explain the effects of switch probability on the executive processes underlying task-switching behavior.