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

Table 1: Behavioural performance in the NBT as reported in Nuerk et al. (2002). RT in ms and percentage of
errors (with SD in parentehesis).
Bisectable
Non-Bisectable
RT in ms Related Unrelated Possible Impossible
Small range 1468 (148) 1594 (140) Large distance 1629 (116) 1599 (132)
Large range 1853 (140) 2029 (125) Small distance 1913 (109) 1846 (147)
Errors in % Related Unrelated Possible Impossible
Small range 3 (3) 4 (4) Large distance 4 (3) 2 (2)
Large range 10 (7) 20 (10) Small distance 13 (5) 7 (5)
Regression analysis: RT data were reanalysed in two regression analyses to
specifically examine the influence of the above described determinants. Note that the
differences between results of the new and the original analysis (see Nuerk et al., 2002, p.
703) are due to the predictors entered in the respective analyses. In the current analysis, range,
decade crossing, sum and multiplicativity were included as predictors in the regression model
for bisected triplets. For non-bisected triplets, range, decade crossing, sum, bisectability and
distance to the mean were included as predictors. Regression models accounted for a
considerable proportion of variance in bisectable (R²=0.52) and non-bisectable RT (R²=0.51;
see Table 2). Range, decade crossing, sum and multiplicativity were significant predictors of
RT in bisected triplets. For non-bisected triplets, range, decade crossing, sum, and distance to
the mean were significant predictors of RT. Although bisectability was not a significant
predictor of RT, we have included it in the general linear model examining fMRI signal in
non-bisected triplets, since the main effect of bisectability was significant in the ANOVA.
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