Developmental changes in line bisection: A result of callosal maturation?

Abstract

Normal adults tend to bisect horizontal lines to the left of the objective middle, especially when using the left hand. This bias has been attributed to the dominance of the right hemisphere in spatial attention. The authors investigated the effect of hand use and line position in visual line bisection in right-handed children and adults, classified into 4 different age groups: 10-12, 13-15, 18-21, and 24-53 years (N = 98). All 4 groups showed the characteristic leftward bias when using the left hand. When using the right hand, the youngest group showed a rightward bias, whereas the other 3 groups all showed a leftward bias. This suggests a shift from contralateral to right-hemispheric control during puberty and may reflect maturation of the corpus callosum.

Line Bisection in the Split Brain.

“…In the case of R.V., then, the bias is more symmetrical and comparable with that previously shown in patients with callosal infarction in, or in a section of, anterior regions of the corpus callosum (Goldenberg, 1986;Heilman et al, 1984;Kashiwagi et al, 1990). It is also similar to the pattern observed in neurological normal young children, who also show symmetrical neglect attributable to callosal immaturity (Bradshaw et al, 1988;Dobler et al, 2001;Hausmann et al, 2003;Roeltgen & Roeltgen, 1989). In the case of L.P., the pattern is closer to that seen in normal adults.…”

Influence of Age and Sex on Line Bisection: A Study of Normal Performance with Implications for Visuospatial Neglect

“…Indeed, only a few studies have examined the separate effects of either age or sex. Four studies that examined the effects of age all report variable results (De Agostini et al, 1999;Failla et al, 2003;Fujii et al, 1995;Hausmann et al, 2003). One reason for such discrepancies in reported findings is the distribution of age and sex grouping involved.…”

“…One reason for such discrepancies in reported findings is the distribution of age and sex grouping involved. One study did not distinguish the sex of their subjects (Hausmann et al, 2003), another reported results but only as a function of sex (De Agostini et al, 1999), while another collapsed results across the sexes (Fujii et al, 1995). All four compared uneven age-cohorts and failed to test subjects across different age groups.…”

Schizophrenia and rightward bias in line bisection

“…The interaction between hand, scan, and group also suggests fluctuations in hemispheric control in the schizophrenia group. With a right-to-left scan, the schizophrenia group showed rightward bias with the right hand and a leftward bias with the left, again suggesting a symmetrical tendency consistent with callosal immaturity (Hausmann et al, 2002;Hausmann, Waldie, & Corballis, 2003b;Jewell & McCourt, 2000). This effect was barely evident in controls.…”