title: Triangular backgrounds shift line bisection performance in hemispatial neglect: the critical point.
abstract: Isosceles triangular backgrounds influence line bisection performance in normal control participants and patients with hemispatial neglect. When the triangles are oriented asymmetrically with the vertex in I visual field, and the base in the other, the perceived midpoint of horizontal lines within the triangle is shifted towards the base, and away from the vertex. The current study examines this illusion further by systematically varying the extent of the triangle presented. With only fragments of the triangle in the background of the line, the vertex is the critical component driving the illusory shift in perceived midpoint. Patients with neglect and controls are equally sensitive to the illusion. Similar geometric illusions that are also intact in neglect, along with these results, suggest that preattentive, implicit visual processing is preserved in neglect and drives these illusions.
authors.affiliation: Geriatric Neuropsychology Laboratory, Geriatric Research, Education and Clinical Center, VA Boston Healthcare System, Massachusetts 02130, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Esterman
authors.forename: Regina
authors.initials: R
authors.lastname: McGlinchey-Berroth
authors.forename: Michael P
authors.initials: MP
authors.lastname: Alexander
authors.forename: William
authors.initials: W
authors.lastname: Milberg
mesh_terms: D000368:Aged; D003072:Cognition Disorders / Q000209:etiology / Q000523:psychology*; D005260:Female; D006801:Humans; D007088:Illusions / Q000523:psychology; D008297:Male; D008875:Middle Aged; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology*; D020521:Stroke / Q000150:complications; D014110:Touch; D014796:Visual Perception / Q000502:physiology*