Lecture 11: Geometrical illusions:

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Lecture 11 Geometrical illusions Recent studies
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Geometrical illusions
Müller-Lyer - line segments of equal
length? Zöllner - parellel lines? Hering - local
orientation contrast? Orbison - bent
lines? Fraser - circles or spirals? Poggendorff -
co-linear? Ponzo - length/size at different
distances (linear perspective) Vertical-horizontal
- equal length? Café wall - parallel
lines? Ebbinghaus - same size? Jastrow - same
shape? Shepherd - same shape?
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Questions What causes the illusion? (functional
, neural) mechanisms Illusion in perceptual vs.
action? (grasping, delayed grasping)
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Muller-Lyer
Blurring? Low spatial frequency?
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Muller-Lyer
But?
Maybe
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Size constancy?
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Ponzo
Linear perspective (Depth) Size constancy?
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Questions What causes the illusion? (functional
, neural) mechanisms Illusion in perceptual vs.
action? (grasping, delayed grasping)
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Titchener illusion
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http//ahsmail.uwaterloo.ca/kin356/illusion/circle
s.HTML
http//www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd
Searchdbpubmedtermtitchenerillusiontoolfuzz
yottitchnerillusion
Kwok RM, Braddick OJ. When does the Titchener
Circles illusion exert an effect on grasping?.
Two- and three-dimensional targets. Neuropsycholog
ia. 200341(8)932-40. Franz VH, Gegenfurtner
KR, Bulthoff HH, Fahle M. Grasping visual
illusions no evidence for a dissociation between
perception and action. Psychol Sci. 2000
Jan11(1)20-5. Pavani F, Boscagli I, Benvenuti
F, Rabuffetti M, Farne A. Are perception and
action affected differently by the Titchener
circles illusion? Exp Brain Res. 1999
Jul127(1)95-101. Aglioti S, DeSouza JF,
Goodale MA. Size-contrast illusions deceive the
eye but not the hand. Curr Biol. 1995 Jun
15(6)679-85.
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Additional Questions Effects of attention on
the illusions? (need attention? Low-level vs.
high-level?) Insights on how the brain
works? (Natural scene statistics?)