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