Mid-Frontal Theta Power Associated With Instruction-Based Modulations in Cognitive Stability and Flexibility

Cognitive stability and flexibility are often conceived as two antagonistic modes of cognitive control. While stability supports the maintenance of a stable task focus and resistance against interference, cognitive flexibility facilitates adaptive responses to changing demands. In a pre-registered electroencephalography study, we investigated the mechanisms underlying adjustments in cognitive stability and flexibility by examining neural signatures of cognitive control adjustments. Specifically, we tested whether deliberate enhancements in cognitive stability and flexibility levels were associated with a facilitation of goal shielding and shifting, respectively. Participants completed a task-switching experiment in which they received explicit strategy instructions that aimed at promoting either cognitive stability or flexibility in a within-subjects design. We assessed mid-frontal theta power as an indicator of cognitive control recruitment and effort mobilization. Participants succeeded in adopting the instructed control states and behaviorally exhibited inverse adjustments in indicators of cognitive stability and flexibility. However, we did not find any differences in theta power in response to shielding or shifting demands between conditions. Consistent with previous studies and subjective effort ratings, more stable control states were further not associated with a generally increased recruitment of cognitive control. We thus did not find that adjustments in cognitive stability and flexibility were linked to modulations in effort or cognitive control recruitment. Potential processes that may have promoted more effective task shielding and shifting are discussed, providing directions for future research.