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

SYNOPSIS
At the end of the general introduction, the main aim of the current thesis was identified
as trying to provide a comprehensive evaluation of the influences of the place-value structure
of the Arabic number system on numerical cognition by a) further establishing the
generalizability of decomposed processing of two-digit number magnitude and b) an
investigation of possible individual and cultural differences. The results of the individual
studies were meaningful to both of these topics and will be discussed accordingly.
The generalizability of decomposed processing of multi-digit numbers
Considering the generalizability of decomposed number magnitude processing, it was
sought to extend existing evidence on four different aspects: (i) the nature of the mental
number line, (ii) the subject of the numerical tasks for which evidence for decomposed
processing was obtained, (iii) the longitudinal developmental influences of place-value
understanding, and (iv) processing specificities of decomposed number magnitude processing
– each of which will be elaborated on in turn.
The nature of the mental number line
Concerning the nature of the mental number line the results of Study 1 observing a
reliable unit-decade compatibility effect for comparisons to a fixed internal (memorized)
standard is hard to reconcile with the assumption of the internal number magnitude
representation being holistic in nature. Instead, the present findings suggest that the mental
number line may also involve representations of the structural characteristics of the Arabic
number system such as its base-10 place-value properties. This latter interpretation is further
corroborated by the results of the patient study (cf. Study 6). Hemispatial neglect not only
affected participants’ performance in a number bisection task regarding analogue scaling
properties but also the processing of place-value information (i.e., increased difficulty when a
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