Figure 1.

ANOVA results. A: Main effect of problem size at an uncorrected voxelwise p-value of < .00001 and cluster size k = 10 voxels: Bilateral intraparietal activation as well as activation of the left angular gyrus and the left retrosplenial cortex. Please note that a stronger p-value of < .00001 had to be used to enable a dissociation of the different maxima of activation (at a p-value of < .005 a cluster of > 10000 voxels covered large parts of bilateral occipital and parietal cortices). B: Main effect of carry at an uncorrected voxelwise p-value of < .005 and cluster size k = 10 voxels: Bilateral intraparietal activation as well as activation of the left angular gyrus and the left retrosplenial cortex. C: Interaction of problem size and carry: In the most difficult condition (i.e., large addition problems with a carry) right intraparietal activation is observed at an uncorrected voxelwise p-value of < .005 and cluster size k = 10 voxels.