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

early place-value understanding for the later development of numerical / arithmetical
competencies (see also Study 2 for influences of the place-value structure of the Arabic
number system on adult addition performance).
Section 4: The neuro-cognitive underpinnings of place-value integration
In Study 5, the neural correlates of place-value integration were investigated by
functional MRI. In a previous study Nuerk, Geppert, van Herten, and Willmes (2002) found
that in a verification version of the number bisection task triplets crossing a decade boundary
were responded to significantly slower than triplets that stayed within the same decade (e.g.,
25_28_31 vs. 23_26_29). The authors interpreted this as indicating the need for additional
processing of place-value information to evaluate the distance between e.g., the second and
the third number when crossing a decade boundary. The interest of the current study was to
examine whether there is a specific neural correlate of place-value processing, implicating a
cortex area with higher neural activity while processing triplets crossing into the next decade
compared to triplets with no decade crossing. As previously observed by Wood, Nuerk, and
Willmes (2006, see also Knops, Nuerk, Sparing, Foltys, & Willmes, 2006), processes of unitdecade
integration were associated with more pronounced activation in the IPS, a cortex
location affiliated with the processing of magnitude information in general. However, as
overall range (i.e., the distance between the two outer numbers) was accounted for in the
parametric analyses for triplets with and without a decade crossing this activation
dissimilarity cannot be explained by differences in holistic magnitude measures. Instead, the
data argue for specific processing demands associated with the required processing of placevalue
information for triplets crossing into the next decade meaning that place-value
information is not only retained in the representation of two-digit number magnitude but also
explicitly processed when participants encounter two-digit numbers. Thereby, these results
indicate a specific neural correlate of place-value processing / integration.
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