Crossover by line length and spatial location

Mark Mennemeier, Steven Z. Rapcsak, Chris Pierce, Elsie Vezey

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


It is well known that line length has a systematic influence on line bisection error in neglect. Most patients with neglect misbisect long lines on the same side of true center as their brain lesion but then cross over on short lines, misbisecting them on the opposite side (i.e., crossover by line length). What is less recognized is that the spatial location of lines relative to the viewer can similarly induce a crossover effect when one considers line bisection error scores that have been averaged across individual line lengths. Patients with right hemisphere injury and neglect classically make averaged line bisection errors that fall right of true center on lines located either at midline or to the left of the viewer; however, we observed that the averaged line bisection error can fall left of true center when lines are located to the right of the viewer (i.e., crossover by spatial location). We hypothesized that crossover by both line length and spatial location stem from systematic errors in magnitude estimation, i.e., perceived line length. We tested predictions based on this hypothesis by examining how the crossover effect by line length is altered by the spatial location of lines along a horizontal axis relative to the viewer. Participants included patients with unilateral lesions of the right and left cerebral hemispheres and age-appropriate normal subjects. All groups demonstrated a crossover effect by line length at the midline location but the effect was altered by placing lines to the right and left of the viewer. In particular, patients with right hemisphere injury and neglect crossed-over across a broader range of line lengths when the lines were located to the right of the viewer rather than at either midline or left of the viewer. It is proposed that mental representations of stimulus magnitude are altered in neglect, in addition to mental representations of space, and that traditional accounts of neglect can be enhanced by including the psychophysical concept of magnitude estimation.

Original languageEnglish (US)
Pages (from-to)412-422
Number of pages11
JournalBrain and Cognition
Issue number3
StatePublished - 2001


  • Hemispace
  • Line bisection
  • Magnitude estimation
  • Mental representation
  • Neglect

ASJC Scopus subject areas

  • Neuropsychology and Physiological Psychology
  • Experimental and Cognitive Psychology
  • Developmental and Educational Psychology
  • Arts and Humanities (miscellaneous)
  • Cognitive Neuroscience


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