Congruency drives “conflict adaptation” independent of conflict: Converging evidence from behavior and computational modeling

While performing distractor-interference tasks, people exhibit smaller congruency effects (i.e., less interference from distractors) after incongruent trials than after congruent trials. The influential conflict-monitoring model (Botvinick et al., 2001) posits that such congruency sequence effects (CSEs) reflect "conflict adaptation": increased control following heightened conflict in a previous trial. An alternative view posits that objective trial congruency (i.e., incongruent vs congruent) triggers increased control independent of conflict. Support for the latter view, however, comes from atypical tasks that lack an overall congruency effect because the distractor appears well before the target. Here, we seek to distinguish between these two views with a more typical task design. First, we simulate, in the context of a confound-minimized flanker task, (1) the conflict monitoring model, wherein conflict triggers control processes to shift attention toward the target and away from the distractors in the next trial, and (2) a proposed new variant of this model, wherein objective trial congruency triggers control processes instead of conflict. Our simulations show that response time correlates with internal conflict in these models and statistically mediates the relationship between congruency and conflict. Thus, the conflict model predicts the congruency effect varies with the previous trial's response time and not its congruency (each controlling for the other), whereas our proposed congruency model predicts the reverse. Second, we show that human data from the same task (n = 48) exhibit the latter data pattern and not the former one, thereby favoring the congruency model of the CSE over the conflict monitoring model.