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

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strictly decomposed model revealed a reliable main effect <strong>of</strong> compatibility [F(1, 39) = 6.03, p<br />

< .05] meaning that estimated RTs for compatible comparisons were significantly shorter than<br />

estimated RTs for incompatible comparisons (496 ms vs. 506 ms, respectively). Moreover,<br />

both <strong>the</strong> main effect <strong>of</strong> unit distance and <strong>the</strong> interaction <strong>of</strong> compatibility and unit distance<br />

were not reliable [both F(1, 39) < 1]. Yet, when evaluating <strong>the</strong> compatibility effect separately<br />

for comparisons with ei<strong>the</strong>r a large or a small unit distance it was found that <strong>the</strong> compatibility<br />

effect was present only for comparisons with a large unit distances [496 ms vs. 508 ms<br />

respectively; F(1, 9) = 13.16, p < .01] but missed significance for <strong>the</strong> comparisons with small<br />

unit distances [498 ms vs. 504 ms respectively; F(1, 29) = 2.02, p = .17, see Figure 3, Panel<br />

C]. Comparably to <strong>the</strong> analyses on <strong>the</strong> data produced by <strong>the</strong> holistic model <strong>the</strong> <strong>influence</strong> <strong>of</strong><br />

<strong>the</strong> covariate problem size was reliable in all analyses [two-way ANOVA: F(1, 39) = 15.27, p<br />

< .001; large unit distance: F(1, 9) = 7.71, p < .05; small unit distance: F(1, 29) = 10.79, p <<br />

.01]. <strong>The</strong>se results not only indicated that <strong>the</strong> strictly decomposed model accounted for a<br />

larger part <strong>of</strong> <strong>the</strong> variance <strong>of</strong> <strong>the</strong> empirical RTs in general, but also showed that <strong>the</strong><br />

compatibility effect was simulated successfully.<br />

Regression<br />

<strong>The</strong> final model <strong>of</strong> <strong>the</strong> stepwise regression analysis on <strong>the</strong> modelled RT data <strong>of</strong> <strong>the</strong><br />

strictly decomposed incorporated <strong>the</strong> predictors difference between <strong>the</strong> logarithms <strong>of</strong> <strong>the</strong> tobe-compared<br />

<strong>number</strong>s, unit distance and logarithmic unit distance [adj. R 2 = .80, R = .90, F(3,<br />

40) = 59.49, p < .001, see Table 5]. A closer look at <strong>the</strong> beta weights revealed that reaction<br />

times increased as <strong>the</strong> overall distance between <strong>the</strong> to-be-compared <strong>number</strong>s decreased and<br />

problem size increased. More particularly, response latencies also increased as unit distance<br />

decreased. As unit distance is positive for compatible pairs but negative for incompatible<br />

<strong>number</strong> pairs <strong>the</strong> inclusion <strong>of</strong> this predictor reflects a reliable <strong>influence</strong> <strong>of</strong> unit-decade<br />

compatibility on response latencies estimated by <strong>the</strong> strictly decomposed model.<br />

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