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

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epresentation itself as well as its increasing importance for <strong>the</strong> numerical capabilities<br />

associated with <strong>the</strong> consecutive developmental steps.<br />

Working Memory<br />

Capacity<br />

Cognitive<br />

Representation<br />

Step 1 Step 2 Step 3 Step 4<br />

Core system <strong>of</strong><br />

magnitude (cardinality)<br />

Verbal <strong>number</strong><br />

system<br />

/one/ /two/ …<br />

<strong>Arabic</strong> <strong>number</strong><br />

system<br />

…, 45, 46, 47, …<br />

Mental <strong>number</strong> line<br />

(ordinality)<br />

Concrete quantity<br />

Number words<br />

Digits<br />

Spatial image<br />

Brain Area Bi-parietal Left prefrontal Bi-occipital Bi-parietal<br />

Ability<br />

Subitizing,<br />

approximation,<br />

comparison<br />

Verbal counting,<br />

counting strategies,<br />

fact retrieval<br />

Written calculations,<br />

odd/even<br />

Approximate<br />

calculation,<br />

Arithmetic thinking<br />

Place-<strong>value</strong> understanding<br />

Infancy Preschool School Time<br />

Figure 1: Model <strong>of</strong> numerical development by von Aster and Shalev (2007, p. 870) adapted and extended by a<br />

representation <strong>of</strong> <strong>the</strong> <strong>place</strong>-<strong>value</strong> <strong>structure</strong> <strong>of</strong> <strong>the</strong> <strong>Arabic</strong> <strong>number</strong> system (broken arrow and shaded<br />

area below)<br />

On a closer inspection <strong>of</strong> <strong>the</strong> quantity representations proposed for Steps 1, 2, and 3 it<br />

has to be noted that only from step 2 on symbolic coding (verbal and digital) is assumed while<br />

step 1 quantity representations rely on non-symbolic coding <strong>of</strong> concrete quantities. This<br />

distinction seems to be motivated by observations suggesting that even preverbal infants are<br />

able to discriminate between numerical quantities (e.g., Feigenson, Carey, & Hauser, 2002;<br />

Feigenson, Dehaene, & Spelke, 2004; Xu, Spelke, & Goddard, 2005; for a review see Cordes,<br />

& Brannon, 2008). <strong>The</strong> <strong>place</strong>-<strong>value</strong> <strong>structure</strong> <strong>of</strong> <strong>the</strong> <strong>Arabic</strong> <strong>number</strong> system first comes into<br />

play with <strong>the</strong> development <strong>of</strong> symbolic quantity representations in step 2 when tens and units<br />

have to be discerned when confronted with <strong>the</strong> respective <strong>number</strong> words. Decomposed<br />

processing <strong>of</strong> tens and units can be assumed to start at this developmental stage as well and to<br />

get more and more automated with increasing age and experience (cf. Pixner, Moeller, Zuber,<br />

& Nuerk, 2009) as it allows for representing any given <strong>number</strong> in a very efficient way by a<br />

309

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