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

this system. In this case no language-specific effects would be predicted. In order to explain
the influence of language properties on the spatial representation system an interaction with
the verbal system needs to be assumed. Such an interaction has been proposed by Nuerk et al.
(2005) who reported language effects in a task as basic as magnitude comparison. Their
results indicated that the verbal representation of numbers interacts with the magnitude
representation, even for the case that numbers are presented in Arabic digital notation. Despite
the fact that magnitude comparisons should be possible to perform without involving the
verbal representations of the respective numbers, Nuerk et al. (2005) suggested that the Triple
Code model does not per se exclude the possibility of a co-activation of the verbal
representation even when it is not of primary relevance for the task at hand.
Considering the current study, the data clearly corroborate the assumption that the
verbal number representation influences the number line task, which is usually assumed to
exclusively assess the spatial representation of number magnitude. A possible explanation of
this influence in the present study may stem from the development of the neural circuitry
underlying numerical cognition. Recent functional MRI studies indicated that the cortex areas
associated with the three representational codes of numerical information are much less
distinct in children than in adults (Kaufmann et al., 2006; Kaufmann et al., 2008; Rivera,
Reiss, Eckert, & Menon, 2005). This means, for the same numerical task children activate a
more wide-spread neural network possibly including activation of several representations in
parallel, even when they are not primarily needed for solving the task. Thus, in number-line
estimation the to-be-estimated numbers seem to co-activate their verbal word frame. In
German-speaking children inverted two-digit number words on the verbal and non-inverted
digital Arabic representation may both be elicited and thus compete for use. When the
influence of the verbal representation is larger for one item it would necessarily determine a
misplacement of the item on the hypothetical number-line. As such an influence would be
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