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

place-value knowledge in numerical development, in particular, when evaluating specific
effects related to the processing of place-value information at different stages of development
and schooling. This is of specific interest as the results of Study 2 of the present thesis showed
that influences of place-value processing are still observable in adult arithmetic (i.e.,
particular processing of the unit digits in two-digit addition when a carry is required). Thus,
there is the possibility that difficulties in early place-value understanding may not only be a
problem restricted to a certain time in numerical development. Instead, impaired place-value
understanding at earlier stages of numerical development may determine later arithmetic
performance even into adulthood. This assumption is further corroborated by the results of a
recent eye-tracking study comparing the eye-fixation behaviour of children and adults in an
addition verification paradigm (Moeller, Klein, & Nuerk, under revision). On the one hand,
results indicated that there are considerable differences as regards the way children and adults
select the correct probe. While children seemed to primarily rely on calculating the correct
result, adults seemed to rely on both verifying the correct probe as well as rejecting the
incorrect probe. On the other hand, the data also showed that the requirement of a carry
specificall increased the processing times of the unit digits of the summands for both children
and adults consistently. Synced with the findings of the current thesis this suggests that basic
principles of place-value processing in mental arithmetic may be acquired early on during
learning arithmetic may not change qualitatively. Thereby, the importance of successful
mastery of place-value principles in early stages of numerical development (cf. discussion and
Figure 1 above) is again emphasized.
However, as already been reported by Miura and colleagues (1989; 1994) there are
considerable differences in the accuracy of place-value processing between children but also
between different countries and languages. Usually, a superiority of Asian over Western
children is observed when it comes to explicitly producing tens and units of a given number.
The authors attributed their finding to the fact that the number word systems of most East
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