Sensation & Perception

Sensation:

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Perception:

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The Visual System

Anatomy of Human Eye -

• From the outside (what you see when looking in a mirror)

  • Sclera:
    

  • Pupil:
    

  • Iris:
    

  • Cornea:
    

• On the Inside:

• Lens:

 

 

• Retina:

 

 

 

 

Types of visual receptors

• Rods:

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• Cones:

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• Fovea:

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• Perpiheral Retina

 

 

• Optic Nerve:

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DEMO:

 

 

Color Perception

Color Vision at Level of the Receptor:

Trichromatic Theory of Color Vision:

 

 

• each receptor is sensitive to light from a different part of visual spectrum -- based on three different cone photopigments.

  • Blue:
    
    

  • Green:
    
    

  • Red:
    
    

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• Color Blindness results when don't have one type of cone receptor working.

Then we can only use 2 cone receptor types to determine color and it creates confusions.

e.g. red-green color blindness:

from 2 causes

1.

 

 

2.

 

 

e.g. yellow-blue color blindness:

 

 

How visual scenes appear to normal, red/green color blind and yellow/blue color blind people.

examples:

Color Vision at level of the neuron carrying color info to the brain:

Opponent-Process Theory:

 

• 3 types

  • Red-Green:
    
    
    
    

  • Yellow-Blue:
    
    
    
    

  • Black-White:
    
    

 

• Explains negative afterimages:

Color Vision at Level of the visual cortex in the brain:

• Visual Cortex has neurons that respond to both color and form.

  e.g. McCollough Effect -- orientation contingent color afterimage