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

systematically neglected the left part of a numerical interval when bisecting it. This shifting to
the right of a numerical interval closely mirrors the difficulties they commonly exhibit when
bisecting a physical line.
However, until now almost all studies that have investigated number processing in
neglect have focused on single-digit numbers (but see Rossetti et al., 2004). Moreover, all
previous studies of neglect and number representation used the production version of the
Number Bisection Task (NBT; e.g. Priftis et al., 2006; Rossetti et al., 2004 and Zorzi et al.,
2002; 2006).
As pointed out by Nuerk, Geppert, van Herten, and Willmes (2002) a production version
of the NBT may not be well-suited for assessing two-digit number processing due to the
increased perceptual and cognitive demands imposed by two-digit numbers. Two-digit
number processing requires the integration of different number representations (Nuerk et al.,
2002): (i) spatial and magnitude information of a number complying with the place x value
structure of the Arabic system (for a review, see Nuerk & Willmes, 2005), as well as (ii) a
number being part of a multiplication table or not (i.e. multiplicativity; Nuerk et al., 2002).
However, Nuerk et al. (2002) showed that such different number representations can be
assessed by a verification version of the NBT. In this verification version participants have to
decide whether the central number of a triplet is also the arithmetical middle between the two
outer numbers (i.e. a bisected triplet, e.g. 22_25_28) or not (i.e. a non-bisected triplet, e.g.
22_27_28).
In particular, Nuerk et al. (2002) observed that, among bisected triplets, multiplicatively
related triplets (e.g. 21_24_27 vs. 22_25_28) were responded to faster and more accurately
than non-multiplicative triplets (e.g. 25_28_31 vs. 22_25_28). As multiplication fact
knowledge can be recruited to solve the task, more time-consuming magnitude manipulations
can be bypassed (Delazer et al., 2006; Nuerk et al., 2002). Additionally, as known from other
calculation tasks (e.g. carry-over effect in addition, Deschuyteneer, De Rammelaere, & Fias,
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