Visual and proprioceptive adaptation to optical displacement were found to decrease with increasing difficulty of mental arithmetic performed during hall exposure. The graded nature of such cognitive interference is consistent with the idea that limited-capacity central control processes are required to coordinate the discordant visual system with other sensorimotor systems. When central processing capacity is diverted to other tasks, the frequency of coordinated activity involving the discordant visual system is reduced, there are fewer occasions for the discordance to pose a problem, and there is less need for adaptive recalibration in any sensorimotor system.