title: Spatial displacement of numbers on a vertical number line in spatial neglect.
abstract: Previous studies that investigated the association of numbers and space in humans came to contradictory conclusions about the spatial character of the mental number magnitude representation and about how it may be influenced by unilateral spatial neglect. The present study aimed to disentangle the debated influence of perceptual vs. representational aspects via explicit mapping of numbers onto space by applying the number line estimation paradigm with vertical orientation of stimulus lines. Thirty-five acute right-brain damaged stroke patients (6 with neglect) were asked to place two-digit numbers on vertically oriented lines with 0 marked at the bottom and 100 at the top. In contrast to the expected, nearly linear mapping in the control patient group, patients with spatial neglect overestimated the position of numbers in the lower middle range. The results corroborate spatial characteristics of the number magnitude representation. In neglect patients, this representation seems to be biased towards the ipsilesional side, independent of the physical orientation of the task stimuli.
authors.affiliation: Division of Neuropsychology, Center of Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen Tübingen, Germany ; Graduate School of Neural and Behavioral Sciences, International Max Planck Research School Tübingen, Germany ; Department of Psychology, University of Tübingen Tübingen, Germany.
authors.forename: Urszula
authors.initials: U
authors.lastname: Mihulowicz
authors.affiliation: IWM-KMRC Knowledge Media Research Center Tübingen, Germany ; Section Neuropsychology, Department of Neurology, University Hospital RWTH Aachen University Aachen, Germany.
authors.forename: Elise
authors.initials: E
authors.lastname: Klein
authors.affiliation: Department of Psychology, University of Tübingen Tübingen, Germany ; IWM-KMRC Knowledge Media Research Center Tübingen, Germany ; LEAD Graduate School, University of Tübingen Tübingen, Germany.
authors.forename: Hans-Christoph
authors.initials: HC
authors.lastname: Nuerk
authors.affiliation: Section Neuropsychology, Department of Neurology, University Hospital RWTH Aachen University Aachen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Willmes
authors.affiliation: Division of Neuropsychology, Center of Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen Tübingen, Germany.
authors.forename: Hans-Otto
authors.initials: HO
authors.lastname: Karnath
keywords: human; mental number line; number line estimation; numbers; space; spatial neglect