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

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three representations proposed are to be localized. While <strong>the</strong> neuro-anatomical correlate <strong>of</strong> <strong>the</strong><br />

analogue magnitude representation remained quite vague in <strong>the</strong> first compositions <strong>of</strong> <strong>the</strong><br />

model (Dehaene & Cohen, 1995; 1997), Dehaene and colleagues (2003) circumscribed <strong>the</strong><br />

cortex sites assumed to be specifically involved in magnitude processing more precisely: On<br />

<strong>the</strong> one hand, <strong>the</strong> core processing <strong>of</strong> quantity information is proposed to be subserved by <strong>the</strong><br />

horizontal parts <strong>of</strong> <strong>the</strong> intraparietal sulcus (IPS) as an abstract and notation invariant<br />

representation <strong>of</strong> magnitude. This magnitude representation is suggested to be spatially<br />

organized by means <strong>of</strong> a left-to-right oriented mental <strong>number</strong> line. When processing<br />

magnitude information <strong>the</strong> corresponding parts <strong>of</strong> this mental <strong>number</strong> line are assumed to be<br />

activated. <strong>The</strong>reby, performing numerical tasks as basic as magnitude comparisons requires<br />

attentional navigating along <strong>the</strong> mental <strong>number</strong> line to integrate <strong>the</strong> necessary information.<br />

Dehaene and colleagues (2003) postulated such processes <strong>of</strong> mental navigation calling upon<br />

<strong>the</strong> spatial attributes <strong>of</strong> <strong>the</strong> mental representation <strong>of</strong> <strong>number</strong> magnitude to be subserved by<br />

posterior superior parts <strong>of</strong> <strong>the</strong> parietal lobe (PSPL) adjacent to <strong>the</strong> (IPS). Thus, in its latest<br />

version <strong>the</strong> Triple Code Model specifically includes a spatial representation <strong>of</strong> <strong>number</strong><br />

magnitude apart from an abstract magnitude code. However, please note that generally<br />

magnitude representation in <strong>the</strong> Triple Code Model is assumed to be holistic in nature,<br />

meaning that multi-digit <strong>number</strong>s are represented as one integrated entity ra<strong>the</strong>r than<br />

decomposed into <strong>the</strong>ir constituting digits. Thus, <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 is not retained in <strong>the</strong> magnitude representation postulated by <strong>the</strong> Triple Code<br />

Model. Finally, <strong>the</strong> neuro-anatomical correlates <strong>of</strong> <strong>the</strong> auditory-verbal representation<br />

(including arithmetic, e.g., multiplication fact knowledge) as well as <strong>the</strong> visual <strong>Arabic</strong> <strong>number</strong><br />

form are suggested to be found in <strong>the</strong> left angular gyrus and <strong>the</strong> temporo-occipetal junction<br />

respectively. Yet, as <strong>the</strong> current <strong>the</strong>sis is primarily concerned with aspects <strong>of</strong> <strong>the</strong> magnitude<br />

representation and in particular with evaluating <strong>the</strong> representation <strong>of</strong> <strong>the</strong> <strong>place</strong>-<strong>value</strong> <strong>structure</strong><br />

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