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Use of Isoluminant StimuliReveals Segregation of Functions
across theMagnocellular vs. Parvocellular
Systems
Properties of M vs. P Neurons
Contrast Sensitivity
P-SystemResolves
ManyLevels of Gray
M-SystemResolves
FewLevels of Gray
Isoluminant Stimulus Paradigm(Simplified B&W Camera Analogy)
Flicker Photometry Stimuli
Counter-Phase Red/Green Flicker
Increase Flicker Rate Until Color Fusion Threshold
Color fusion threshold usually around 12-15 Hz.
Adjust Intensity of Green StimulusUntil Luminance Flicker Minimized
The values of the Red and Green stimuli at the point of complete flicker fusionestablishes the ISOLUMINANT POINT for the current observer.
REMEMBER:
The M-system is insensitive toIsoluminant Stimuli
ASSUMPTION:
Perceptual Abilities Lostunder IsoLuminant Conditionsare Mediated by the M-system
Depth/Size Scaling
• Size Constancy• Ponzo Illusion• Muller-Lyer Illusion• Texture Gradients
• Stereopsis• Motion Parallax
Size Constancy
Ponzo Illusion
Müller-Lyer Illusion
Green-on-Red Stimulus Format
Depth/Distance from Texture Gradients
Depth from Motion ParallaxSony Wii Demo
Motion Analysis
• Structure from Motion
• Synchronized Apparent Motion(Grouping by Proximate Motion)
Structure from Coherent Motion
http://www.michaelbach.de/ot/col_equilu/index.html
Grouping by Motion
Frame-1 Frame-2
Grouping by Motion
Grouping by Motion
Grouping by Motion
Figure/Ground Segregation
• Rubin’s Vase
• Subjective Contours(Kaniza figures)
Rubin’s Vase
Subjective Contours
Subjective Contours
Object Perception
• Binding Primitive Features into Objects
• Grouping by Colinearity(AI: “Block World”)
Grouping by Colinearity(“Block World”)
Appendix