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

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eview), questions concerning representational universality / generality versus specificity are<br />

still under debate. <strong>The</strong>refore, it was <strong>the</strong> aim <strong>of</strong> <strong>the</strong> current <strong>the</strong>sis to provide converging<br />

evidence for <strong>the</strong> existence and <strong>the</strong> importance <strong>of</strong> <strong>the</strong> <strong>place</strong>-<strong>value</strong> <strong>structure</strong> <strong>of</strong> <strong>the</strong> <strong>Arabic</strong><br />

<strong>number</strong> system being retained in <strong>the</strong> human representation <strong>of</strong> <strong>number</strong> magnitude. This issue<br />

was pursued by evaluating effects possibly driven by separate representations <strong>of</strong> <strong>the</strong><br />

individual power levels <strong>of</strong> multi-digit <strong>number</strong>s in a variety <strong>of</strong> numerical tasks, using different<br />

methodologies and assessing diverse populations. However, before turning to a more explicit<br />

description <strong>of</strong> <strong>the</strong> present <strong>the</strong>sis recent evidence suggesting <strong>the</strong> <strong>place</strong>-<strong>value</strong> <strong>structure</strong> <strong>of</strong> <strong>the</strong><br />

<strong>Arabic</strong> <strong>number</strong> system to be represented in <strong>the</strong> human understanding <strong>of</strong> <strong>number</strong> semantics<br />

will be reviewed briefly.<br />

Fur<strong>the</strong>r evidence for decomposed processing <strong>of</strong> tens and units<br />

In recent years evidence for <strong>the</strong> existence <strong>of</strong> decomposed processing <strong>of</strong> <strong>number</strong><br />

magnitude has accumulated. Extending <strong>the</strong> original results recent studies also using a <strong>number</strong><br />

comparison paradigm revealed that <strong>the</strong> <strong>influence</strong> <strong>of</strong> <strong>the</strong> <strong>place</strong>-<strong>value</strong> <strong>structure</strong> <strong>of</strong> <strong>the</strong> <strong>Arabic</strong><br />

<strong>number</strong> system on numerical cognition is generally language invariant (Moeller, Fischer,<br />

Nuerk, & Willmes, 2009a; Verguts & De Moor, 2005), although slightly moderated by<br />

characteristics <strong>of</strong> a language’s <strong>number</strong> word system (Nuerk et al., 2005; Pixner, 2009), starts<br />

early in numerical development (Nuerk, Kaufmann, Zoppoth, & Willmes, 2004b; Pixner,<br />

Moeller, Zuber, & Nuerk, 2009), and is relatively independent from literacy (Wood, Nuerk,<br />

Freitas, Freitas, & Willmes, 2006a for data <strong>of</strong> Brazilian semi illiterates). Fur<strong>the</strong>rmore, Moeller<br />

et al., 2009a showed that separate processing <strong>of</strong> tens and units is performed in parallel ra<strong>the</strong>r<br />

than sequentially as suggested by Poltrock and Schwartz (1984). Moreover, Wood, Nuerk,<br />

and Willmes (2006b) were able to pinpoint <strong>the</strong> neural correlates <strong>of</strong> <strong>place</strong>-<strong>value</strong> integration<br />

(i.e., <strong>the</strong> compatibility effect) to <strong>the</strong> depths <strong>of</strong> <strong>the</strong> intraparietal sulcus (IPS, see also Goebel,<br />

17

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