Error-preceding brain activity links neural markers of task preparation to cognitive stability and flexibility

Balancing stability and flexibility is required to facilitate successful task selection in situations with competing stimuli. Research suggests a set of counteracting control processes that maintains this balance. In the present study, we investigate how two neural correlates of task preparation in event-related potentials (ERPs), the mixing positivity and the switch positivity, can be linked to stability and flexibility in task selection. In a cued task switching paradigm, we analyzed deviations of these ERPs when task confusions occurred, that is, when participants erroneously executed the currently irrelevant task. We found a reduced mixing positivity to be a main source of task confusions in a task environment that required ongoing switches between competing tasks, whereas the switch positivity was uninvolved here. However, an overabundance of this latter component was a source of task confusions in a task environment that required the repetitive execution of the same task, although task switches were not required at all in this condition. These results not only highlight the distinct functional significance of the two preparatory ERPs and show that control processes can be maladaptive in certain contexts. They can also be utilized to locate the mixing positivity and the switch positivity on the stability-flexibility spectrum. Our results are in line with accounts that suggest that a balance between stability and flexibility is facilitated by the concurrent involvement of two control processes. One that manages the top-down bias of the relevant task set and one that increases or decreases competition between alternatively available stimuli.