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

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Non-monotonous Model <strong>of</strong> <strong>the</strong> Relation<br />

between <strong>the</strong> Distance Effect and Arithmetic Performance<br />

Ari<strong>the</strong>mtic Performance<br />

Low numerical capability<br />

High task complexity<br />

Size <strong>of</strong> <strong>the</strong> Distance Effect<br />

High numerical capability<br />

Low task complexity<br />

Capability/complexity range<br />

Rousselle & Noel (2007)<br />

Current Study<br />

Capability/complexity range<br />

Holloway & Ansari (in press)<br />

Kaufmann & Nuerk (2008)<br />

Figure 2: A hypo<strong>the</strong>tical curvilinear model <strong>of</strong> a non-monotone relationship between <strong>the</strong> distance effect and<br />

arithmetic performance (see text for details). It is suggested that <strong>the</strong> size <strong>of</strong> <strong>the</strong> distance effect might be<br />

determined by two factors: First, increasingly precise and automatic access to <strong>the</strong> magnitude representation<br />

(i.e., higher capability) decreases <strong>the</strong> explained variance <strong>of</strong> <strong>the</strong> distance effect. Second, <strong>the</strong> distance effect also<br />

depends on <strong>the</strong> error variance which is increased by backup strategies (e.g., counting) necessary for tasks <strong>of</strong><br />

very high complexity. However, too much <strong>of</strong> such non-systematic error variance may diminish <strong>the</strong> distance<br />

effect or even make it disappear. <strong>The</strong> model in Figure 2 accounts for <strong>the</strong> seemingly antidromic correlations <strong>of</strong><br />

<strong>the</strong> distance effect and arithmetic capabilities by assuming that <strong>the</strong> numerical capability as well as task<br />

complexity differ between <strong>the</strong> cited studies. In Rousselle and Noël’s (2007) study, capability is very low<br />

(dyscalculic children) while in our study relative task complexity is very high (two-digit <strong>number</strong> comparison for<br />

first graders). In this capability/complexity range, a higher distance effect is particularly associated with less<br />

error variance (e.g., less backup strategies) so that a larger distance effect indicates better numerical<br />

competencies and better arithmetic performance. O<strong>the</strong>r studies (e.g., Holloway & Ansari, 2009) employed a<br />

less complex task (single-digit comparison) and <strong>the</strong> participants should have had higher individual capabilities<br />

(as older children were assessed). For such individually simple tasks, no backup strategies (which boost error<br />

variance) are to be expected in normally developing children. <strong>The</strong>refore, a smaller distance effect might <strong>the</strong>n<br />

indicate more efficient access to <strong>the</strong> magnitude representation leading to a negative relation between <strong>the</strong><br />

distance effect and arithmetic performance in this capability/complexity range. Please note that this model<br />

remains to be tested empirically, however, at <strong>the</strong> moment it <strong>of</strong>fers a possible explanation for seemingly<br />

contradictory results.<br />

Working memory and later arithmetic performance<br />

<strong>The</strong>re was one o<strong>the</strong>r somewhat unexpected finding in our data. CE and visuo-spatial<br />

WM capacity were positively correlated with <strong>the</strong> carry effect or <strong>the</strong> error rate for carry<br />

163

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