Conflict adaptation depends on task structure.

The dependence of the Simon effect on the correspondence of the previous trial can be explained by the conflict-monitoring theory, which holds that a control system adjusts automatic activation from irrelevant stimulus information (conflict adaptation) on the basis of the congruency of the previous trial. The authors report on 4 experiments showing that conflict adaptation is mediated by task structure as well as previous congruency. Experiment 1 showed that for 2 completely segregated sets of stimulus-response pairs there was no conflict adaptation across sets. However, if the stimulus sets overlapped for 2 separate response sets, conflict adaptation could be observed across the response sets. Experiment 2 showed that this effect was not due to the use of stimulus-response sets lateralized to 1 hemisphere each. Experiment 3 showed that if response sets are common for 2 separate stimulus sets, then conflict adaptation can again be observed across sets. Finally, Experiment 4 showed local control effects in the absence of confounding feature-overlap effects. These results indicate that deployment of control as evidenced by conflict adaptation reflects task structure.