Outline 10/20/98

3 Common Principles across sensory systems

Transduction,

Neural Coding

Interaction

Interaction in Time: Adaptation

Interaction in Space: Contrast

Perception

 

 

 

Some Examples of Sensory Interaction from Vision

 

 

The Anatomy of the Eye

The Retina

 

Rods and Cones

 

Duplex Theory of Vision

Rods--operate under low illumination and are relatively achromatic. Think of them as night time receptors.

 

Cones--operate under high illumination. Chromatic. Packed around fovea. Think of them as daytime receptors.

 

Interaction in Time: Adaptation

Adaptation--Repeated stimulation of a particular receptor leads to reduced responding.

 

 

A demonstration--peripheral vision, adaptation, and movement.

 

 

Color Afterimage: Another demonstration of interaction across time

 

 

Why does color afterimage work? Adaptation and "Opponent Processes"

Every hue (i.e., color) has a complementary hue. When mixed together, these two hues form gray.

Two pairs are crucial--blue/yellow and red/green.

Why? Because they are antagonists--meaning that when they are balanced, we perceive gray.

 

 

Interaction is Space: Contrast

In vision, the response in one receptor region depends upon how neighboring receptor regions are responding.

 

 

Brightness Contrast

 

Color Contrast--the Chromatic counterpart to brightness contrast.

 

 

From Sensation to Perception Color vs. Movement Afterimage

 

Color Afterimage--Retinal Processing

 

 

Motion Afterimage--Cortical Processing