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

2005), triplets in which the interval crossed a decade boundary were more difficult than
triplets in which the interval did not cross into the next decade (e.g. 22_25_28 vs. 25_28_31,
see Nuerk et al., 2002).
For non-bisected triplets it was easier to classify triplets with a far distance of the
(presented) central number to the actual arithmetical middle than triplets with a central
number close to the arithmetical middle (e.g. 21_22_29 vs. 21_24_29; arithmetical middle
25). Most importantly, for the present study, an effect of the relative size of the central
number was found (Nuerk et al., 2002; Moeller, 2006). Triplets with a central number smaller
than the arithmetical middle of the interval (i.e. a relatively small central number within the
interval, e.g. 18_19_32) are easier to reject than triplets with a central number larger than the
arithmetical middle of the interval (e.g. 18_31_32).
But how do these item characteristics affect neglect patients? As elaborated above,
neglect patients neglect the left side of a presented numerical interval. They do so in a
production task and in particular for one-digit numbers. We suggest that this effect of neglect
on the number magnitude representation generalizes to the full range of two-digit numbers
and to the verification version of the NBT. Therefore, for non-bisected triplets we hypothesize
that, unlike in healthy participants, the advantage for triplets involving central numbers
smaller than the arithmetical middle of the numerical interval should be less pronounced or
even disappear in neglect patients compared to non-neglect controls. If an interaction with
distance to the middle were observed, the effect of size relative to the arithmetical middle
should be more prominent for triplets with far distances to the middle and less prominent for
close distances to the middle. This should be observed because, for far distances, the central
number is much farther into the neglected part of the mental numerical interval.
For bisected triplets we do not expect strong modulations of the multiplicativity effect as
this effect is not related to the spatial representation of number magnitude and was observed
even in the absence of any distance effects in a patient with posterior cortical atrophy (Delazer
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