Perception Notes

There are five things we are going to look at:

Sensation
Gestalt
Vision
Rods & Cones

Perception is a combination of sensation (collecting input stimuli) and the process of understanding what all the inputs mean.

Sensation
- sensory input
- Hermann’s grid
1. Perception
- Organizing sensory input
- Interpreting sensory input
- Recognizing objects
- Extracting meaning
- Linear model
  - perception
  - recognition
  - action
  - stimulus
  - transduction
  - neural activity
  - knowledge
- Not that simple
  - Bottom-up
  - Top-down
    - Stroop Effect
      - Red
      - Orange
      - Blue
      - Green
  - Canonical Perspective
  - Rat-Man art
  - Cognitive Psych
    - round hole; oval
Gestalt
- Doesn’t translate easily to English
- configuration, form, holistic, structure, and pattern.
- How phenomena become organized into whole meaningful figures
- Visual perception is an active creation
- not merely the adding up of lines and movement.
- “The whole is different than the sum of it’s parts.”
- Max Wertheimer
  - Challenge’s Wundt structuralism
  - Perception is more than parts
  - Phi Phenomenon
  - Apparent motion effect
- 6 Gestalt principles
  - phi phenomenon
  - figure and ground
    - Characteristics
      - Bounded (closed)
      - Symmetrical
      - Brighter
      - Smaller
      - Convex
  - ClosureSee objects as whole
    - Missing pieces are interpolated
  - Similarity
    - form
    - angle
  - Proximity
    - Objects close to each other are associated together
  - Pragnanz
    - simplicity and regularity
3. Vision
- Light
  - electromagnetic
  - frequency
    - wave length
      - longer is slower
      - color spectrum
  - amplitude = how tall wavewave height is
    - intensity
    - absorb and reflect
- Source
  - see object’s reflection
  - everything but purpole is absorbed
  - relative distance
  - color and smoothness
- Eye
  - cornea (2/3 of eye’s focus)
  - aqueous humor
  - pupil
  - iris
  - lens
  - vitreous humor
  - dead spot
- Occipital lobe
  - dorsal stream
    - where you & things are
  - temporal stream
    - what you are seeing
    - object recognition
    - Inferior Temporal Cortex
      - identifying objects
      - Cells respond to physical
      - Also to what viewer perceives
    - Figure & background
      - Respond same way even if change position, size and angle
    - Identifying objects
    - Important for shape constancy
    - Face recognition
    - fusiform gyrus of inferior temporal cortex
      - Left = recognizes “face-like” features in objects
      - Right = determines if actual face
    - Faces
    - Car model identification
    - Bird species
- Rods & Cones
  - 2 types of visual receptors
  - 2 separate systems
  - A. Scotopic
    - Rods
    - Black & white
    - Poor quality
    - Fast response, low light
    - Target detection
  - B . Photopic
    - Cones
    - Color
    - High quality
    - Slow, lots of light
    - Target identification
  - Rods
    - Inside rods:
      - cell nucleus
      - fiber ending in a single end-bulb (a rod spherule)
    - Connect to bipolar cells
    - Many rods to one ganglion
      - Spatial summation
    - Rods are peripheral
      - Low quality images
      - Intensity & shades of gray
      - Sensitive to lots of wavelengths
    - Cones are centralized
      - Day vision
      - Target identification
      - Slow processing
      - High quality images
      - Color
        
        Sensitive to specific wavelengths
      - Structure
        
        Shorter, broader, and more tapered than rods
        
        Have no visual purple
      - Contain 1 of 3 photopigments
        
        long
        
        medium
        
        short
      - Each fovea cone
        
        Direct line to brain
        
        Exact location of point of light
4. Color
- Molecules absorb light
  - Even molecules come in colors
  - If hit by light, molecule changes
  - Chromophore
    - Form of Vitamin A
    - Photons changes it shape
- Causes activation of large protein called an opsin
- Opsin Comparison
  - Several types, similar process
  - Rods
    - Thermally stable
    - Rhodopsin
  - Cones
    - Less stable
    - Photopsins
      - Long = Red region
      - Medium = Green region
      - Short = Blue region
- Respond to range of wavelengths
  - Not just one color
  - Varies with light intensity
- Different combos of 3 pigments
  - Each cone detect all colors
- Level of energy need varies
- Color is pattern of photo receptor activity
  - yellow: L more than M
  - red: L much more than M
- Green is easy to see
- 3 Color receptors (plus B-W)
  - Long = slow red light
  - Medium = medium green light
  - Short = fast blue light
  - Rods = intensity
- Retina output
  - 1.5 million ganglion cells
  - fovea: some cones 1:1
  - fovea edge: some cones 5:1
  - periphery: thousands:1
- Spatially encodes images
  - Filters & compresses data
  - 100 times more receptors than ganglion cells
- Spontaneously firing base rate
  - Increase rate = excitation
  - Decrease rate = inhibition
5. Theories of color
- A. Trichromatic
  - Young-Helmholtz Theory
  - 3 types of cones
  - doesn’t explain red-green color blindness
  - doesn’t explain afterimage
- B. Opponent-Process Theory
  - Paired opposites:
    - white-black
    - red-green
    - yellow-blue
  - Afterimages from fatiguing
  - Prolonged stimulation
  - doesn’t explain color constancy
- C. Retinex Theory
  - Recognize color as light changes
  - Cortex compares inputs
  - Determines appropriate bright

Color Vision

Notes

Here are the class notes for TOPIC.

Perception is a combination of sensation (collecting input stimuli) and the process of understanding what all the inputs mean.

Sensation
- sensory input
- Hermann’s grid
1. Perception
- Organizing sensory input
- Interpreting sensory input
- Recognizing objects
- Extracting meaning
- Linear model
  - perception
  - recognition
  - action
  - stimulus
  - transduction
  - neural activity
  - knowledge
- Not that simple
  - Bottom-up
  - Top-down
    - Stroop Effect
      - Red
      - Orange
      - Blue
      - Green
  - Canonical Perspective
  - Rat-Man art
  - Cognitive Psych
    - round hole; oval
Gestalt
- Doesn’t translate easily to English
- configuration, form, holistic, structure, and pattern.
- How phenomena become organized into whole meaningful figures
- Visual perception is an active creation
- not merely the adding up of lines and movement.
- “The whole is different than the sum of it’s parts.”
- Max Wertheimer
  - Challenge’s Wundt structuralism
  - Perception is more than parts
  - Phi Phenomenon
  - Apparent motion effect
- 6 Gestalt principles
  - phi phenomenon
  - figure and ground
    - Characteristics
      - Bounded (closed)
      - Symmetrical
      - Brighter
      - Smaller
      - Convex
  - ClosureSee objects as whole
    - Missing pieces are interpolated
  - Similarity
    - form
    - angle
  - Proximity
    - Objects close to each other are associated together
  - Pragnanz
    - simplicity and regularity
3. Vision
- Light
  - electromagnetic
  - frequency
    - wave length
      - longer is slower
      - color spectrum
  - amplitude = how tall wavewave height is
    - intensity
    - absorb and reflect
- Source
  - see object’s reflection
  - everything but purpole is absorbed
  - relative distance
  - color and smoothness
- Eye
  - cornea (2/3 of eye’s focus)
  - aqueous humor
  - pupil
  - iris
  - lens
  - vitreous humor
  - dead spot
- Occipital lobe
  - dorsal stream
    - where you & things are
  - temporal stream
    - what you are seeing
    - object recognition
    - Inferior Temporal Cortex
      - identifying objects
      - Cells respond to physical
      - Also to what viewer perceives
    - Figure & background
      - Respond same way even if change position, size and angle
    - Identifying objects
    - Important for shape constancy
    - Face recognition
    - fusiform gyrus of inferior temporal cortex
      - Left = recognizes “face-like” features in objects
      - Right = determines if actual face
    - Faces
    - Car model identification
    - Bird species
- Rods & Cones
  - 2 types of visual receptors
  - 2 separate systems
  - A. Scotopic
    - Rods
    - Black & white
    - Poor quality
    - Fast response, low light
    - Target detection
  - B . Photopic
    - Cones
    - Color
    - High quality
    - Slow, lots of light
    - Target identification
  - Rods
    - Inside rods:
      - cell nucleus
      - fiber ending in a single end-bulb (a rod spherule)
    - Connect to bipolar cells
    - Many rods to one ganglion
      - Spatial summation
    - Rods are peripheral
      - Low quality images
      - Intensity & shades of gray
      - Sensitive to lots of wavelengths
    - Cones are centralized
      - Day vision
      - Target identification
      - Slow processing
      - High quality images
      - Color
        
        Sensitive to specific wavelengths
      - Structure
        
        Shorter, broader, and more tapered than rods
        
        Have no visual purple
      - Contain 1 of 3 photopigments
        
        long
        
        medium
        
        short
      - Each fovea cone
        
        Direct line to brain
        
        Exact location of point of light
4. Color
- Molecules absorb light
  - Even molecules come in colors
  - If hit by light, molecule changes
  - Chromophore
    - Form of Vitamin A
    - Photons changes it shape
- Causes activation of large protein called an opsin
- Opsin Comparison
  - Several types, similar process
  - Rods
    - Thermally stable
    - Rhodopsin
  - Cones
    - Less stable
    - Photopsins
      - Long = Red region
      - Medium = Green region
      - Short = Blue region
- Respond to range of wavelengths
  - Not just one color
  - Varies with light intensity
- Different combos of 3 pigments
  - Each cone detect all colors
- Level of energy need varies
- Color is pattern of photo receptor activity
  - yellow: L more than M
  - red: L much more than M
- Green is easy to see
- 3 Color receptors (plus B-W)
  - Long = slow red light
  - Medium = medium green light
  - Short = fast blue light
  - Rods = intensity
- Retina output
  - 1.5 million ganglion cells
  - fovea: some cones 1:1
  - fovea edge: some cones 5:1
  - periphery: thousands:1
- Spatially encodes images
  - Filters & compresses data
  - 100 times more receptors than ganglion cells
- Spontaneously firing base rate
  - Increase rate = excitation
  - Decrease rate = inhibition
5. Theories of color
- A. Trichromatic
  - Young-Helmholtz Theory
  - 3 types of cones
  - doesn’t explain red-green color blindness
  - doesn’t explain afterimage
- B. Opponent-Process Theory
  - Paired opposites:
    - white-black
    - red-green
    - yellow-blue
  - Afterimages from fatiguing
  - Prolonged stimulation
  - doesn’t explain color constancy
- C. Retinex Theory
  - Recognize color as light changes
  - Cortex compares inputs
  - Determines appropriate bright

Notes

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Notes

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