Schizophrenia and rightward bias in line bisection

Abstract

This study investigated line bisection in 10 males with schizophrenia and 15 controls. There was an overall leftward bias, consistent with slight right "pseudoneglect", but the schizophrenia group showed more variation with experimental conditions, suggesting impaired interhemispheric transfer. Specifically, the rightward bias was especially marked when the lines were positioned on the right side of the page, when the right hand was used, and when a right to left scan was adopted. The rightward bias was associated with the predominance of negative symptoms. Findings are discussed with reference to the role of the corpus callosum in the transfer of spatial attention.

Hemispheric asymmetry and callosal integration of visuospatial attention in schizophrenia: A tachistoscopic line bisection study

“…The earliest study (Mather et al, 1990) reported a significant leftward bisection error for control subjects, and no significant difference between the patient and control groups. A study by Barnett (2006) also found leftward errors for control subjects, but the errors made by patients did not differ significantly from zero. Two studies from the same laboratory Michel et al, 2007) reported bisection errors in control subjects that were not significantly different from zero, and significant leftward errors for patients.…”

Asymmetries of Visuospatial Attention in Schizophrenia

“…Thus, dopamine antagonists might have a normalizing or balancing effect, thereby decreasing both positive symptoms (e.g., delusions, hallucinations) as well as right neglect [76,77]. On the other hand, the association between left neglect in PS and overall negative symptomatology was suggested by Barnett [47]. This view was in agreement with the study by Mayer et al [78] who showed that SP with flat affect ("negative symptoms") were characterized by greater right hemisphere deficit than left hemisphere deficit.…”

“…Barnett [47] found that individuals with greater overall negative symptomatology made greater rightward deviations in right hemispace. Furthermore, Benson and Park [49] observed that the magnitude of right deviations was strongly related to delusional ideation.…”

“…Barnett [47] examined the influence of some factors on line bisection, namely line position (left, centre, right), hand and scanning direction (left to right, right to left). Barta et al [47] observed that PS deviated further to the right with respect to the control group when they (1) bisected lines placed on the right side of the page and (2) when they used the right hand and the direction of scanning was from right to left. The presence of a rightward bias was subsequently confirmed by Rao et al [48] and Benson and Park [49].…”

“…The relationship between bisection performance and clinical profile of PS with left hemi-inattention was investigated, performing correlations between bisection errors and Positive And Negative Syndrome Scale [47,49], Brief Psychiatric Rating Scale [49] and Delusions Inventory [49] scores. Barnett [47] found that individuals with greater overall negative symptomatology made greater rightward deviations in right hemispace.…”