Object-based neglect in number processing.
Recent evidence suggests that neglect patients seem to have particular problems representing relatively smaller numbers corresponding to the left part of the mental number line. However, while this indicates space-based neglect for representational number space little is known about whether and --if so --how object-based neglect influences number processing.To evaluate influences of object-based neglect in numerical cognition, a group of neglect patients and two control groups had to compare two-digit numbers to an internally represented standard. Conceptualizing two-digit numbers as objects of which the left part (i.e., the tens digit should be specifically neglected) we were able to evaluate object-based neglect for number magnitude processing.Object-based neglect was indicated by a larger unit-decade compatibility effect actually reflecting impaired processing of the leftward tens digits. Additionally, faster processing of within- as compared to between-decade items provided further evidence suggesting particular difficulties in integrating tens and units into the place-value structure of the Arabic number system.In summary, the present study indicates that, in addition to the spatial representation of number magnitude, also the processing of place-value information of multi-digit numbers seems specifically impaired in neglect patients.
Section Neuropsychology, Department of Neurology, University Hospital, RWTH Aachen University, Aachen, Germany. klein@neuropsych.rwth-aachen.de
Elise
E
Klein
Korbinian
K
Moeller
Daniela
D
Zinsberger
Harald
H
Zauner
Guilherme
G
Wood
Klaus
K
Willmes
Christine
C
Haider
Alfred
A
Gassner
Hans-Christoph
HC
Nuerk
D000368:Aged; D000375:Aging / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D009483:Neuropsychological Tests; D010468:Perceptual Disorders / Q000523:psychology*; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology