The processing of Arabic numbers is under cognitive control

In this study, we evaluated whether the processing of two-digit Arabic numbers is subject to cognitive control. Participants performed a number comparison task with unit–decade compatible trials (36–47) and unit–decade incompatible number pairs (37–46). The unit–decade compatibility (incompatible minus compatible trials) was considered an index of conflict situation in numerical processing. To examine whether participants adapted to numerical conflict, we manipulated the percentage of incompatible trials relative to the percentage of compatible trials (20, 50, 80 % incompatible trials). The unit–decade compatibility effect was modulated by the amount of incompatible trials: the compatibility effect decreased progressively as the percentage of incompatible trials increased. This result indicated that participants adapted to numerical conflict. The findings are discussed in terms of cognitive control. Implications for models of two-digit number processing are also addressed.