In this task, developed by Eriksen (1974), subjects are asked to press a left-hand or right-hand response key depending on the direction indicated by a central arrow. The task is made challenging by flanking the central arrow with rows of other arrows, which can point in either the same direction (congruent) as the central arrow or in the opposite direction (incongruent condition)(Eriksen & Eriksen, 1974). The dependent measures in this task are the reaction time differences between congruent and incongruent trials. Opposite flankers cause response conflict and thus require cognitive control, the degree of which is correlated with activation of the ACC (Casey et al., 2000). For the reversal learning task, the final reaction time score (reaction time difference between incongruent and congruent conditions) was the dependent measure used for analyses.
