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

of overall distance necessarily requires a holistic no such a predictor should be incorporated in
the final regression model evaluating the data produced by the strictly decomposed model.
Finally, due to reasons of model parsimony the hybrid model should only be chosen to be the
most appropriate model when it outperforms the strictly decomposed model reliably.
Evaluation of the data produced by either of these models yielded results that were
straightforward on all of these aspects. First, a reliable influence of the numerical distance
between the to-be-compared numbers on RT was present in the data produced by each of the
three computational models. Thereby, indicating that the distance effect was successfully
accounted for by all three models for both, comparisons to a variable (as e.g., in Nuerk et al.,
2001) as well as to a fixed standard (as e.g., in Moeller et al., 2009b; Study 1 of the present
thesis). Second, as regards unit-decade compatibility our hypothesis was confirmed as the
compatibility effect could not be observed for the data produced by the holistic model in
general. Concerning the hybrid and the strictly decomposed model the results on the
compatibility effect were less consistent. Although, the empirical data was accounted for
comparably well by the strictly decomposed as well as the hybrid model in terms of
descriptive adequacy, the compatibility effect could be simulated by both the strictly
decomposed as well as the hybrid model only for the case of comparisons to a variable
standard. Moreover, here, even the characteristic interaction of compatibility and unit distance
was observed. The compatibility effect for modelled item RTs was consistently larger for
number pairs with a large unit distance as compared to pairs with a small unit distance.
Additionally, the categorical effect was specified by the results of the stepwise regression
analyses for both the decomposed and the hybrid model. Unit distance was identified to be a
reliable predictor of item RT for both models. Item RT increased as unit distance decreased.
As unit distance is positive for compatible but negative for incompatible number pairs this
again indicated the influence of unit-decade incompatibility on simulated item RTs.
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