Conflict resolution in two-digit number processing: evidence of an inhibitory mechanism

We investigated the mechanism involved in conflict resolution when individuals processed two-digit numbers. Participants performed a comparison task in blocks of two trials. In the first trial, between-decade two-digit numbers were used in a compatible condition where the decade and the unit of one number were larger than those of the other number (i.e., 21–73) and an incompatible condition where the decade of one number was larger but the unit was smaller than those of the other number (i.e., 61–53). In the second trial, within-decade two-digit numbers were presented in a related condition where the numbers contained the units presented previously (i.e., 41–43) and an unrelated condition with units that did not appear before (i.e., 48–49). In the first trial, participants responded more slowly in incompatible trials relative to compatible trials. In the second trial, participants were slower in the related condition relative to unrelated trials only after incompatible trials. These results suggest that participants experienced conflict in the incompatible condition of first trial and that they inhibited irrelevant units to resolve conflict.