title: Effect of practice versus information on the visual illusion.
abstract: OBJECTIVE
  The Muller-Lyer illusion is a visual illusion in which a horizontal shaft with an inward-pointing chevron (fins-out) affixed to each end is perceived longer than a shaft with outward-pointing chevrons (fins-in). The goal of this study was to compare the effects of experience and knowledge about the Muller-Lyer illusion on participants' perceptual precision.
  
  
  METHODS
  Participants were undergraduate students (n = 108) who were not familiar with the Muller-Lyer illusion prior to the experiment. The task of participants was to adjust one movable line to make it equal to the other in Muller-Lyer figure. They received ascending and descending Muller-Lyer trials in three blocks with 20 trials each. The Experimental Group received information about the Muller-Lyer illusion prior to the third block.
  
  
  RESULTS
  For the Experimental Group, the amount of departure in Block 3 was reduced significantly compared with previous blocks.
  
  
  CONCLUSIONS
  Knowledge about the mechanisms underlying visual illusions may play an important role in helping individuals overcome them.
authors.affiliation: Mashhad Medical Sciences University, Mashhad, Iran.
authors.forename: Abbas A
authors.initials: AA
authors.lastname: Khorasani
authors.forename: Javad S
authors.initials: JS
authors.lastname: Fadardi
authors.forename: Marziyeh S
authors.initials: MS
authors.lastname: Fadardi
authors.forename: W Miles
authors.initials: WM
authors.lastname: Cox
authors.forename: Jafar T
authors.initials: JT
authors.lastname: Sharif
mesh_terms: D000328:Adult; D001921:Brain / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D005260:Female; D006801:Humans; D007088:Illusions / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008297:Male; D008959:Models, Neurological; D009483:Neuropsychological Tests; D009949:Orientation / Q000502:physiology; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation; D012727:Sex Characteristics; D014796:Visual Perception / Q000502:physiology*