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

Further evidence for place-value influences from more complex tasks and mental
arithmetic
Place-value information in the number bisection task
In the number bisection task triplets involving a decade crossing (e.g., 23_27_31) were
more difficult to evaluate than triplets staying within the same decade (e.g., 21_25_29; Nuerk
et al., 2002; see also the following discussion on Study 5 below). This is particularly
remarkable as this specific item property is not primarily important for solving the task.
Instead, the number bisection task was originally assumed to rely on a default solution
strategy of magnitude manipulations upon the holistic mental number line, only (e.g.,
Dehaene & Cohen, 1997; Cohen & Dehaene, 2000). Building on this considerations of
performance in the number bisection task to be driven primarily by analogue number
magnitude representations (seeing each triplet as a cut-out part of the mental number line),
thus, may indicate that place-value information is nevertheless represented by the mental
number line. This interpretation is supported by the results of the patient study (Study 5). Not
only did the neglect patients exhibit performance impairments associated with them
neglecting the left part of the mental number line (cf. Zorzi, Priftis, & Umiltà, 2003) and thus
the numerically left part of each triplet also for the whole range of two-digit numbers. More
specifically, they had particular problems for decade crossing triplets. The decrease of
performance accuracy due to a decade crossing was more pronounced for the neglect patients
than for the participants of the control group. On a representational level this may suggest that
the processes of integration place-value information are particularly impaired in hemispatial
neglect. Furthermore, it was observed that the decade crossing effect for neglect patients
interacted with the position of the decade crossing within the triplet. Neglect patients’
performance was reliably worse in triplets in whom the decade crossing occurred between the
first and the second number (e.g., 28_32_36) compared to the second and third number (e.g.,
24_28_32). So, in addition to their impairment determined by neglecting the relatively smaller
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