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

For 80 bisected triplets the factors multiplicativity (yes vs. no) and decade crossing (yes
vs. no) were manipulated. Bisected triplets could not be fully crossed, as triplets which are
part of a multiplication table larger than three would always cross into the next decade.
Therefore, the factors decade-crossing (yes vs. no) and multiplicativity (yes vs. no) were
assessed in distinct item sets.
The three numbers were presented above each other in the centre of the screen’s right
half. Each two-digit number extended 7 cm horizontally and 4.5 cm vertically. The numbers
were vertically separated by 4.5 cm. The stimuli were presented in bold Arial font (size 48),
white on black background.
In this study neglect patients’ performance in the verification version of the NBT was
compared to that of non-neglect controls.
Procedure: The experiment was run on a 1.6 GHz laptop and participants were seated
approximately 50 cm in front of a 15´´ screen driven at a resolution of 1024x768 pixels.
The left and right arrow keys located at the bottom right-hand corner of the keyboard
functioned as response buttons: bright orange stickers with the letters “J” for “yes” (in
German “Ja”) and “N” for “no” (in German “Nein”) covered the left and right arrow keys,
respectively. All other keys were covered up with white cardboard. Participants were
instructed to indicate their decision by pressing one of the two response buttons as fast and as
accurately as possible.
The instruction was followed by 20 practice trials incorporating one- and two-digit
numbers. To ensure that patients perceived the presented numbers correctly all participants
were asked to read out the numbers of the first four practice trials aloud. All patients were
able to do so without mistakes. Participation in the critical experiment was only allowed when
more than 2/3 (14 out of 20) practice trials were classified correctly. The experiment involved
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