Effects of task-switch proportion and strategy instructions on cognitive stability and flexibility

To meet the challenges of daily life, we must continuously adapt to optimize the balance between cognitive stability and flexibility depending on the current task demands. The control dilemma theory posits that cognitive stability and flexibility are polar opposites on the same dimension incurring opposing costs and benefits, resulting in a trade-off. Accordingly, a shift towards flexibility (i.e., reducing costs of task-switching) incurs costs in stability (i.e., increasing interference costs), and vice versa. Here, we manipulated the list-wide proportion of task-switches between a flexibility (75% task-repeats) and a stability (25% task-switches) condition. We interspersed coveted trial sequences with balanced task transitions between strongly biased sequences while retaining the list-wide 75:25 ratios. Additionally, we asked participants to adapt to the prevalent transition type by behaving more flexible or stable. We hypothesized that switch costs would be reduced within the flexibility condition, that simultaneously reduced interference in the stability condition would be indicative of a trade-off, and that both control adaptations would persist within the balanced trial sequences. In a within-subjects design, participants (N = 96) completed two online sessions of a classic cued task-switching paradigm. While we did not observe the hypothesized trade-off in either of the two sequence types, the level of flexibility was adapted within the biased sequences, but this effect decayed within the balanced sequences. Taken together, these results highlight that individuals are able to adapt cognitive control modes supporting cognitive flexibility remarkably fast in response to dynamic changes in the likelihood of local trial transitions.