No need to choose: Independent regulation of cognitive stability and flexibility challenges the stability-flexibility trade-off.

Abstract

Adaptive behavior requires the ability to focus on a current task and protect it from distraction (cognitive stability), as well as the ability to rapidly switch to another task in light of changing circumstances (cognitive flexibility). Cognitive stability and flexibility have been conceptualized as opposite endpoints on a stability-flexibility trade-off continuum, implying an obligatory reciprocity between the two: Greater flexibility necessitates less stability, and vice versa. Surprisingly, rigorous empirical tests of this critical assumption are lacking. Here, we acquired simultaneous measurements of cognitive stability (congruency effects) and flexibility (switch costs) on the same stimuli within the same task while independently varying contextual demands on these functions with block-wise manipulations of the proportion of incongruent trials and task switches, respectively. If cognitive stability and flexibility are reciprocal, increases in flexibility in response to higher switch rates should lead to commensurate decreases in stability, and increases in stability in response to more frequent incongruent trials should result in decreased flexibility. Across three experiments, using classic cued task-switching (Experiments 1 and 3) and attentional set-shifting (Experiment 2) protocols, we found robust evidence against an obligatory stability-flexibility trade-off. Although we observed the expected contextual adaptation of stability and flexibility to changing demands, strategic adjustments in stability had little influence on flexibility, and vice versa. These results refute the long-held assumption of a stability-flexibility trade-off, documenting instead that the cognitive processes mediating these functions can be regulated independently-it is possible to be both stable and flexible at the same time.

Beyond stimulus–response rules: Task sets incorporate information about performance difficulty.

“…However, none of the higher-order interactions were observed reliably, in that switch costs were not consistently modulated by the proportion congruent manipulation or by task phases across the experiments (mean switch cost by experiment, phase, and task are displayed in Table A3). This observation runs counter to expectations that increased task focus would lead to larger switch cost (e.g., Dreisbach, 2012; Goschke, 2003) but it aligns well with findings from another recent study, wherein the authors concurrently manipulated the proportion of congruent trials and of switch trials in a task switching protocol similar to the one used in the current study (Geddert & Egner, 2022). Akin to the results presented here, there was no effect of the rate of congruent trials on switch costs (and no effect of the rate of switch trials on congruent effect) in that study (Geddert & Egner, 2022), which suggests that switch costs and congruency effects can in principle be independent of each other (reviewed in Egner, 2023).…”

“…The RT data of Experiments 1a and b fully conformed to our expectations about baseline and learning phase performance, and thus allowed the crucial question of transfer of demand settings to be tested. Specifically, the two tasks elicited equivalent cross-task congruency effects at baseline, the RT task by congruency interaction effects in the baseline phase were nonsignificant in all experiments: 1a (p = .77), 1b (p = .55), 2a (p = .69), 2b (p= .71), 3 (p = .71), and the learning phase successfully induced the expected proportion congruent effect, whereby mean congruency effects were significantly reduced for the low proportion congruent compared to the high proportion congruent task, replicating classic proportion congruent effects (e.g., Braem et al, 2019;Bugg & Crump, 2012) in the domain of cross-task interference (e.g., Geddert & Egner, 2022). The subsequent transfer phase revealed that the proportion congruent effects (and by inference, the level of focus associated with each task) during the learning phase persisted.…”

“…This effect has been attributed to “cross-talk” (interference) in processing due to the ambiguous nature of the stimulus, which can cue either task set, and—in the case of an incongruent mapping—cues opposing responses under the two sets (Koch & Allport, 2006; Rogers & Monsell, 1995; Steinhauser & Hübner, 2007). Based on the assumption that the degree of such cross-talk would be small when the irrelevant stimulus associations are successfully ignored, and high when they are not, many authors have taken the size of the cross-task congruency effect as an index of the relative degree of task focus on, or shielding of, the current task set (e.g., Braem, 2017; Dreisbach & Fröber, 2019; Geddert & Egner, 2022). In line with this literature, we consider congruent trials as requiring a low task focus level to be performed correctly, and incongruent trials as requiring a high task focus level to be performed correctly, and we interpret the size of the congruency effect as an inverse metric of task focus, such that a smaller congruency effect indicates greater task focus (because the participant was more successful at focusing on the task-relevant and ignoring the task-irrelevant stimulus features).…”

“…We expected the manipulation of the rate of (in)congruent trials in the learning phase to produce an adaptation in task focus level, whereby participants would impose a higher focus level on the task that was associated with more incongruent trials. This would be expressed in a “proportion cross-task congruent effect,” where the mean congruency effect is reduced in the task where incongruent trials are frequent compared to the task where incongruent trials are rare (e.g., Geddert & Egner, 2022). This data pattern is widely interpreted as reflecting adaptation of task focus level to contextual demands (Botvinick et al, 2001; for review, see Bugg & Crump, 2012).…”

You can(’t) always get what you want: When goal persistence requires flexibility.

“…In line with this argument, Geddert and Egner (2022) recently showed that different measures of cognitive flexibility versus stability during task switching—the switch costs and the task rule congruency effect—are affected independently from each other with an orthogonal manipulation of the respective contextual demands (i.e., proportion of task switches and proportion of incongruent trials). They ascribed this finding to the different mechanisms that account for switch costs on the one side and congruency effects on the other.…”