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

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meaning that larger problem size was associated with longer response latencies. This suggests<br />

that neglect patients were not only able to perceive <strong>the</strong> decade digits <strong>of</strong> <strong>the</strong> involved two-digit<br />

<strong>number</strong>s but also processed <strong>the</strong>ir magnitude.<br />

Fur<strong>the</strong>rmore, a strong main effect for decade-crossing was found for both speed and<br />

accuracy [RT: F(1, 16) = 34.59, p < .001, accuracy: F(1, 16) = 15.95, p < .001]. Triplets that<br />

did not cross a decade boundary were responded to faster (4620 ms) and more accurately (5.4<br />

% errors) than triplets which crossed into <strong>the</strong> next decade (5195 ms and 16.3 % errors).<br />

Exclusively for response latencies this effect was even fur<strong>the</strong>r differentiated: while nonneglect<br />

controls benefited (-168 ms) from a decade crossing occurring between <strong>the</strong> first and<br />

<strong>the</strong> central <strong>number</strong> <strong>of</strong> a triplet (e.g. 28_31_34 vs. 25_28_31), this had a deteriorating effect on<br />

neglect patients [+908 ms, t(16) = 2.79, p < .05]. This suggests that <strong>the</strong> cognitively more<br />

demanding processing <strong>of</strong> a decade crossing is especially impaired when it occurs in <strong>the</strong><br />

neglected part <strong>of</strong> <strong>the</strong> numerical interval.<br />

Moreover, <strong>the</strong> ANOVA revealed a reliable difference between neglect patients and nonneglect<br />

controls for RT [F(1, 16) = 5.85, p < .05] as well as errors committed [F(1, 16) = 8.06,<br />

p < .05]. So, neglect patients exhibited longer response latencies (6330 ms) and made more<br />

errors (17.4 %) compared to non-neglect controls (3485 ms and 4.2 % errors).<br />

Multiplicativity: A main effect for multiplicativity was observed nei<strong>the</strong>r for RT nor for<br />

errors [RT: F(1, 16) < 1, errors: F(1, 16) = 2.02, p = .17]. However, neglect patients and nonneglect<br />

controls differed significantly in respect to errors committed [F (1, 16) = 11.23, p <<br />

.01] but not for response latencies [F (1, 16) = 1.09, p = 31]. Neglect patients’ performance<br />

was more error prone (24.2 % errors) than that <strong>of</strong> non-neglect controls (7.3 % errors). Finally,<br />

multiplicativity and participant group did not interact reliably for ei<strong>the</strong>r RT or errors [RT: F(1,<br />

16) < 1, errors: F(1, 16) < 1].<br />

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