Line bisection performances of 650 normal children Peter van Vugt a, *, Ingrid Fransen a , Wouter Creten b , Philippe Paquier c, d a Unit of Neurolinguistics, CBL-UIA, Universiteitsplein 1, B-2610, Wilrijk, Belgium b Laboratory for Biomedical Physics and Statistics, University of Antwerp (RUCA), Belgium c Department of ENT-Surgery, School of Medicine, University of Antwerp (UIA), Belgium d Department of Neurology, University Hospital Erasme, Free University of Brussels (ULB), Belgium Received 17 September 1998; received in revised form 28 June 1999; accepted 25 July 1999 Abstract When bisecting lines, an important number of brain damaged patients tend to place their bisection marks in the hemispace ipsilateral to their lesion. Biases have also been reported in normal adults. In vertical bisection both patients and normal subjects present with upward shifts, although a downward displacement may occur eventually. Surprisingly, little is known on line bisection (LB) in normal or brain damaged children. A total of 650 subjects, aged 7±12 years, performed a horizontal and vertical LB task with their preferred hand. Asymmetry indices (AIs) were used to measure directional bias. Unsigned AIs served to evaluate accuracy and mastery of the LB skill. In vertical bisection a general and signi®cant upward bias was found, whereas in horizontal bisection subject (gender, handedness, utilized hand, age) and stimulus variables (orientation, length, position) yielded signi®cantly dierent AIs. Although with increasing age signi®cantly increasing accuracy was observed, none of the participating children mastered LB to mathematical precision. Dierences in IQ-level and attention test score did not yield signi®cantly dierent AIs. Impact from reading pro®ciency could not be demonstrated. It is suggested that stimulus length eect results are compatible with the Halligan and Marshall [Halligan, P., and Marshall, J. Toward a principled explanation of unilateral neglect. Cognitive Neuropsychology, 1994, 11, 167±206] model of hemispatial neglect. Moreover, data may support the hypothesis of greater hemispheric specialization of visuo-spatial skills in boys than in girls. # 2000 Elsevier Science Ltd. All rights reserved. Keywords: Hemispatial neglect; Children; Normed data; Hemispheric lateralization 1. Introduction Hemispatial neglect (HN) is an acquired cluster of symptoms characterized by a failure to orient, report or respond to stimuli located in one hemispace [21,49]. The phenomenon may or may not occur with con- fusion, motor weakness or visual ®eld defects. Left HN following right hemisphere stroke is associated with poor functional recovery [19,49]. Most often, head and body midline are used to divide space in two half-®elds. Traditionally, HN is detected and evaluated along the horizontal dimension, although it may also occur along the vertical (with the upper or lower part neglected) and radial (with under- estimation of far or near parts) axes [41,47,57]. Degree and modality may vary: auditory, olfactory, tactile and visual HN have been reported [19,53]. It appears that HN is an attentional rather than a sensory disorder [25,36,42], but some evidence suggests that visuo- motor [7,10] or representational [2,24] components might be implicated as well. Typically, left HN is reported in adult (right- handed) patients with right parietal brain damage, but cases of HN due to right frontal lobe [31,32], bilateral parieto-occipital [41,58], subcortical [12,16] or callosal [26] lesions have also been reported. Neglect behaviour due to damage of the language dominant hemisphere is thought to be masked by aphasia [29]. However, the higher incidence of left HN has also been explained as Neuropsychologia 38 (2000) 886±895 0028-3932/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved. PII: S0028-3932(99)00130-X www.elsevier.com/locate/neuropsychologia * Corresponding author. Tel.: +32-3-820-2960; fax: +32-3-820- 2957.