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

problem of capitalizing on differences in and between individual variance by using reaction
times in children, error rates seemed to the more reliable measure of task performance to us.
Second, we did not record reaction times for the transcoding task as it is questionable
up to which point in time reaction time should be defined. Considering response onset (i.e.,
starting to write down the first digit) seems inappropriate as transcoding, especially for multidigit
numbers, is a lengthy and often sequential process in which the correct digital symbols
have to be arranged in the correct order. Thus, such a measure of reaction time would not
reflect the end of the transcoding process but only a sub-step on the way to the correct result.
On the other hand, taking the time until the answer is completed would be to measurement
error due to differences in motor and writing skills, the child being distracted or even
restarting transcoding after losing track of the solution. Finally, in most cases only reaction
times of correctly solved trials are analyzed. However, in the current study we were explicitly
interested in what kind of errors the children committed. Most importantly, reaction times are
not capable of coding what kind of error a child made, which was the critical question in the
current study. Therefore, it was decided to run all subsequently described analyses on arcsine
transformed error rates.
Please note that incorporating gender into the analyses revealed no reliable influences
of gender, neither in the factorial nor in the regression analyses. Therefore, the data for boys
and girls was pooled for all analyses reported.
RESULTS
Intelligence and Working Memory
In first grade, average intelligence level as assessed by the CFT 1 (Cattell et al., 1997)
was T = 59 (95% CI: 57.7 – 60.9). At the same time children’s average score in the visuospatial
WM task (Corsi block) was 4.10 (95% CI: 3.96 – 4.23). In the verbal WM task (letter
repetition) the average score was 4.31 (95% CI: 4.17 – 4-44). The mean score of both
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