Exploring the mechanisms underlying conflict adaptation

Human cognition is remarkedly flexible and can inhibit unwanted actions as well as alter behaviours to successfully navigate rapidly changing social environments. Laboratory tasks such as the Stroop test can gauge one’s ability to suppress task-irrelevant information on a given trial. Yet the congruency-sequencing effect (Gratton et al., 1992) reveals that such performance is not constant throughout the task and fluctuates on a trial-by-trial basis. The reduced Stroop effect following an incongruent trial is considered an adaptive behaviour intended to minimise the experience of subsequent conflict and, therefore, is also known as conflict adaptation. Although well documented, the precise mechanisms underpinning conflict adaptation are unknown, although three key accounts emerge: Conflict Monitoring (Botnivick et al., 2001); Repetition Expectancy (Gratton et al., 1992; Egner, 2007), and Feature-Integration (Hommel, 1998; Hommel et al., 2004). The first two are top-down accounts that suggest the dorsolateral prefrontal cortex (DLPFC) is responsible for attentional adjustments to facilitate successful performance. They differ in that the Conflict-Monitoring model is a reactive account that proposes the DLPFC is recruited via conflict detection from the anterior cingulate cortex (ACC) and therefore, upregulation of attentional control towards either the task-relevant or task-irrelevant stimulus is determined by the conflict experienced on the previous trial. Whereas the Repetition Expectancy Model is a proactive account that proposes an anticipatory recruitment of the DLPFC via gated-dopamine release (Braver et al., 2007). Finally, the Feature-Integration account suggests that the task-relevant and task-irrelevant stimulus on each trial form an episodic memory file and it is the complete or partial repetition of one or both the stimulus features that produces the congruency-sequencing effect