Lecture Goals
    Introduce Sensation & Perception
    Introduce Vision
    Introduce Visual illusions
 

Corresponding Readings
    pgs. 153 - 163, 181 - 201
 
 
 

Sensation  =_____________________________________________

    Senses detect certain energies only
        Can't see:
            - X-Rays
            - UV Rays
            - Infrared Rays

    Very sensitive to energies we're aware of
        - 1 gram of salt in 500 liters of water
        - 1 drop perfume in 3 room apartment
        - Wing of a bee on cheek
        - Ticking watch from 20 feet
        - Candle flame from 30 miles
 

Flow of Light into Eye
    - Pupil (hole)

    - Iris (colored eye muscle)

    - Lens (______________________________)
 
 

    - Retina
        = back of eye (inside)

        = "____________________"

        = images UPSIDE DOWN
 

Feature Detectors
    Brain detects many features of visual scene

    Examples
        - contours
        - horizontal/vertical/diagonal lines
        - motion

    Feature detection problems with brain or eyes
 
 

Accommodation = _______________________________________________________________

    Acuity Problems:

        near sighted (___________ images = blurry)

            = image focused _________ retina
 
 

        far sighted (____________ images = blurry)
 
           = image focused ____________ retina
 
 

Retinal Surface
    2 types of light receptor cells:

        Rods for _________ vision

        Cones for ____________ vision
 

Rods
    See world as ______________________________

    Located in the _______________ of retina

    Rod messages ____________
        - increases sensitivity to light (requires less)
        - decreases acuity (sharpness of image)
 
 

Cones
    Responsible for _____________ vision

    Located in ____________ of Retina (_____________)

    Each cone sends own message
        - decreases sensitivity to light (requires more)
        - increases acuity (sharpness of image)
 
 

Blind Spot
    Cone and rod signals sent to brain by optic nerve

    __________________ at back of eye where optic nerve connects to eye (optic disk)

    Blind spot in vision (Finger example)

    Brain "fills in" the gap
 

Color Vision
    Color is psychological

    3 Types of cones:

        - _____ cones

        - _____ cones

        - _____ cones

    All colors = combos of ________________________
 
 
 
 
 
 
 
 

    Trichromats = normal color vision

    Dichromats
        - most can't distinguish RED-GREEN

    Monochromats = see no colors
 
 
 

    Opponent-Processing Theory

        Later in visual process

        3 pairs of color receptors

            - Red OR Green

            - Blue OR Yellow

            - Black OR White
 
 

    Color is not absolute
    Color = context dependent
    * Web Demonstration *
 
 

Perception = ___________________________________________
    = Select what to process
        - attention is selective
        - can't process everything at once
        - focus awareness on set of sensations
 

    Selective Attention Examples
 
 

    Visual capture
        Vision = primary sense
            - vision wins in conflict
            - old movies
            - omiverse theaters
            - motion sickness
 

Perceptual Organization
    Without organization = meaningless
 
 
 
 
 
 

    With organization = meaningful
 
 
 
 

    Gestalt Principles
        Whole = more than sum of parts
            Example - Necker Cube
 
 

        Form Vision
            Figure vs. Ground (selective atten.)
            Examples (vases, words, patterns)
            - role of expectancy & reversibility
 
 

    Grouping Principles
        After figure-ground discriminations
        Organize parts into meaningful whole

 
        Shape
 
 
 
 

        Color
 
 
 
 

        Proximity
 
 
 
 

        Continuity
 
 
 
 
 

        Closure
 
 
 
 

        Connectedness
 
 
 
 

        Contrast
 
 
 
 

        Expectency (non-Gestalt)
 
 
 
 

        Movement
            Drum Corps Example
            Web Example
 
 

Depth Perception
    2 dimensional image on retina (height and width)
 
    Ability to see 3D is innate (visual cliff)
 
 
 

      Binocular Depth Cues

            1) _____________________

                2 eyes separated (2.5 inches)

                Each eye gets __________________________
 
 

            2) __________________________

                Eyes converge more for __________ objects
 
 
 
 
 

                Eye position cues brain
 
 
 
 

        Monocular Depth Cues

            Relative Size:
                - larger = ____________

                - smaller = ___________
 
 

            Interposition:
                - obj. in front = _________

                - object behind = _________
 
 

            Relative Motion:
                - closer than fixation = backwards
                - farther than fixation = forwards
                - closer = faster
 
 

            Relative Clarity:
                - clearer = _______________

                - hazier = ________________
 
 
 

            Texture Gradient:
                - more space between = _____________

                - less space between = ______________
 
 

            Relative Height:
                - before horizon lower = ___________

                - after horizon higher = ____________
 
 

            Linear Perspective:
                - more parallel = _____________

                - closer to intersection = _______
 
 

            Relative Brightness (Shading):
                - brighter = _______________

                - dimmer = _______________
 

        Are at the root of many illusions
            - Web examples