The influence of the place-value structure of the Arabic number ...

von Cramon, 2004) and inhibition of a cognitive set (Konishi, Jimura, Asari, & Miyashita,
2003). Such mechanism may monitor the occurrence of information dispensable or redundant
for solving the NBT, but which can be useful to solve it more efficiently. We will elaborate
more on this point in the next section and relate it to the processing of multiplicativity and
distance to the correct mean.
Monitoring numerical information from different sources and inhibition
Activation of the superior frontal gyrus and the angular gyrus have been associated
with the monitoring of information from different sources (Brass and von Cramon, 2004),
inhibition of a cognitive set (Konishi et al., 2003) and verification of rules (Skosnik et al.,
2002), respectively. In the current study, the angular gyrus was activated when numerical
distance to the mean was large, when no decade crossing occurred, and when triplets were
part of a multiplication table (Figures 1B, 2A and 3, respectively). The superior frontal gyrus
bilaterally and the posterior cingulate gyrus, were also activated in these contrasts as well as
the supramarginal cortex for the contrasts small distance to the mean > large distance to the
mean and no decade crossing > decade crossing. Despite a great disparity between the
numerical properties represented in these contrasts, there is a crucial similarity common to all
of them. They all convey a procedural rule, which, when correctly applied, were useful for
solving a triplet. When the middle number was numerically close to one of the outer numbers
– being consequently far from the correct mean- (e.g. 32_33_41), computations might be
interrupted, as it is very unlikely that the central number is the correct mean of the interval.
Similarly, when no decade crossing occurred, the decade digits might be ignored, since they
were all in the same decade (e.g. 92_95_98). Furthermore, when a triplet was part of a
multiplication table, the central number is per definition the mean of the interval. Always
when these rules can be applied, further computations involving magnitude comparison were
unnecessary. However, information about decade crossing and multiplicativity is not
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