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

124 10024, see Deloche & Seron, 1982; Power & Dal Matello, 1990 for a taxonomy of
transcoding errors), about one half of the German speaking children’s transcoding errors were
related to inversion (e.g., forty-three – spoken as three and forty in German – was written as
34). Thus, when number words are not transparent in regard of the place-value system,
successful integration of tens and units into the place-value system becomes even more
difficult. Taken together, these findings nicely illustrate, that especially for multi-digit
numbers transcoding not transparent notational formats poses specific difficulties on children
as it requires elaborate understanding and application of rules in reference to the place-value
structure of the Arabic number system. (e.g., Proios, Weniger, & Willmes, 2002; Zuber et al.,
2009).
Furthermore, children’s specific difficulties in the acquisition of the place-value
concept do not only become evident from their transcoding errors. Even in tasks as basic as
two-digit number magnitude comparison, children are need to understand and more or less
automatically apply place-value rules. For example, when comparing 42 and 57 tens and units
need to be put in the correct bins (e.g., Nuerk, Weger, & Willmes, 2001), meaning that one
has to segregate which digits represent the to-be-compared decades (i.e., 4 < 5) and which the
units (i.e., 2 < 7). Such unit-decade identification within the place-value system is especially
important when the presented number pair is unit-decade incompatible; meaning that the unit
digit of the smaller number is larger than the unit digit of the larger number (e.g., 47_62, 4 <
6, but 7 > 2). Above chance performance in incompatible trials requires necessarily – at least
some implicit – place-value understanding (see Table 1; for examples and illustration).
Furthermore, it has to be noticed that even for children and adults with an elaborate placevalue
understanding, unit-decade incompatibility is associated with increased response
latencies and error rates (i.e., the so-called unit-decade compatibility effect) as for
incompatible number pairs the separate comparisons of tens and units result in antidromic
decision biases (e.g., Nuerk et al., 2001; Nuerk, Weger, & Willmes, 2004b; Korvorst &
133