illusions what are they? what can we learn from them? d.j. aks 11/10/09 proseminar lecture for z....
TRANSCRIPT
ILLUSIONS
What are they?
What can we learn from them?
D.J. Aks 11/10/09Proseminar Lecture for Z. Pylyshyn, RUCCs
Photo credit: Andy Goldsworthy
ILLUSIONS
Correspondence Problem
Appearance vs. Reality
ILLUSIONS
Discrepancy between…
physical & perceptual stimulus
Mueller-Lyer Illusion
ILLUSIONSDiscrepancy between
physical & perceptual stimulus
Poggendorff Illusion
ILLUSIONSDiscrepancy between
2D & 3D info
Andy Goldsworthy
Experiments & Illusions
http://aks.rutgers.edu/…illusions/Pogg/HalfCircDrag.html
ILLUSIONS
Discrepancy between….?
2D & 3D info
ILLUSIONS
Discrepancy between….?
2D depiction of 3D infoi.e., conflicting perspective of parts of object
• SIZE CONSTANCY - the stability of perceived size despite changes in objective distance and retinal image size.
• CONSTANCY SCALING -
• Our mind adjusts retinal size to correct for registered viewing distance
= Size Distance Scaling
• SIZE CONSTANCY - the stability of perceived size despite changes in objective distance and retinal image size.
• CONSTANCY SCALING -
• MOON ILLUSION - moon appears larger near the horizon than when high in the sky
• Depth cues (on land) give impression that moon is at a "far" distance.--
Thus, we ‘expect’ a far object (moon) to appear small on the retina - but when it does not, the mind compensates and we see the object (moon) as large
Size-contrast
Violation of assumptions
• We tend to assume:
• 1) overhead lighting• SHADING
• 2) regularity of..• SHAPE
Shading&
Structure
Rodin
ILLUSIONS THAT VIOLATE
ASSUMPTIONS Overhead lighting• SHADING - we perceive convex shape when top is lit
& concave when lit at bottom
ILLUSIONS THAT VIOLATE
ASSUMPTIONS
Overhead lighting
• SHADING - we perceive convex shape when top is lit & concave when lit at bottom
ILLUSIONS THAT VIOLATE
ASSUMPTIONS
Overhead lighting & Shading
ILLUSIONS THAT VIOLATE
ASSUMPTIONS SHAPE & SIZE CONSTANCY - apparent shape of an
object remains constant despite changes in the shape of the retinal image -
– REGULAR SHAPES
– AMES ROOM
ILLUSIONS THAT VIOLATE
ASSUMPTIONS SHAPE & SIZE CONSTANCY
– REGULAR SHAPES– AMES ROOM ILLUSION
Occlusion & Shape Perception
Does shape of occluder drive shape percept of ‘occludee’?How about orientation of edges w/in occluder shapes?
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Camouflage & Occlusion
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Occlusion & Shape Perception
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Motion & Shape Perception
Kinetic Depth Effect
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Motion & Shape Perception
Johansson
Neuronal Interactions, Attention & Eye-movements
Visual-Auditory Integration
Sound localization & ventriloquism
Kevin Johnson on David Letterman
http://www.youtube.com/watch?v=DnNBgIKOvr4
Experiments & Illusions
http://aks.rutgers.edu/…illusions/Pogg/HalfCircDrag.html