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Sensation

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Title: Sensation


1
Sensation Perception
2
The Forest Has Eyes Bev Doolittle
3
I. General Characteristics of Sensation
  • A. Basic Definitions
  • 1. Sensation the process by which our sensory
    receptors and nervous system receive and
    represent stimulus energies from our environment
  • 2. Perception The process of organizing and
    interpreting sensory information, enabling us to
    recognize meaningful objects and events

4
Processing
  • 3. Bottom-up-processing analysis that begins
    with the sense receptors and works up to the
    brains integration of sensory information
  • AKA Sensory Anaylsis
  • 4. Top-down-processing information processing
    guided by higher level mental processes as when
    we construct perceptions drawing on our
    experience and expectations.
  • AKA Interpretation of what our senses detect

5
The Forest Has Eyes Bev Doolittle
Bottom Up- sensory systems detect the lines,
angles and colors that form the horses, rider and
surroundings. Top-Down- consider the
paintings title, we notice the hidden
expressions, and direct our attention to those
aspects.
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B. An example of Top-Down Processing
  • 1. E.H. is a patient who can see individual
    features of a face, but cannot see the face as a
    whole.
  • Shown a familiar face her autonomic nervous
    system will respond but she will be unable to
    identify the face.
  • 2. Her problem was top down because the
    information was correctly being sent by the eyes.
    The brain however was not processing the
    information properly.
  • 3. Prosopagnosia complete sensation without
    complete perception

8
Selective Attention
  • The focusing of conscious awareness on a
    particular stimulus.
  • Your five senses take in 11 million bits of info
    per second
  • You consciously process about 40
  • Unconsciously your mind makes use of the other
    million upon million bits
  • You dont realize but your nose is in your line
    of vision.
  • SELECTIVE ATTENTION TEST

9
Inattentional Blindness
  • Failing to see visible objects when out attention
    is directed elsewhere.
  • At the level of conscious awareness, we are
    blind to all but a tiny fraction of stuff
    occurring in front of us.

10
Change Blindness
  • Failing to notice changes in the environment.
  • A form of inattentional blindness.

11
  • In this experiment a man asks for directions from
    the older gentleman. During the process two
    construction workers walk in between the two.
    During this process the man asking for directions
    is switched with another man. Our selective
    attention (focusing on giving directions)
    distracts from the details of the scene.

12
  • Mindfulness - our awareness of and attention to
    what is taking place.
  • Brown Ryan Mindful Attention Awareness Scale

13
  • Range 15-90
  • Higher scores reflect greater mindfulness or
    greater attention to and awareness of current
    experiences.
  • People with higher scores tend to be more
    observant of what is occuring both internally
    externally.
  • Average Score 55.8

14
  • 1. Psychophysics the study of relationships
    between the physical characteristics of stimuli,
    such as their intensity, and our psychological
    experience of them

15
Sensing the World
16
  • Absolute Threshold
  • a. Absolute threshold the minimum stimulation
    needed to detect a particular stimulus 50 of the
    time
  • the absolute threshold varies among individuals

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  • Signal detection
  • a. predicts how and when we detect the presence
    of a faint stimulus amid background stimulation
  • b. Assumes that there is no single absolute
    threshold and that detection depends partly on a
    persons experience, expectations, motivation and
    level of fatigue
  • Subliminal Stimulation
  • a. We can sense stimuli below our threshold
  • b. The controversy first arose over a claim that
    movie theatres were inserting subliminal messages
    into their movies
  • c. Much of our information processing occurs
    automatically, out of sight, off the radar screen
    of our conscious mind.

19
  • b. Operates on two assumptions
  • that we can sense stimuli below the threshold
  • without our awareness these stimuli have
    extraordinary suggestive powers
  • c. Subliminal below ones absolute threshold
    for conscious awareness

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  • d. Studies supporting subliminal perception
  • Krosnick Others 1992 flashed either a bad
    image or good image before showing a persons
    face - the bad image created a bad image of the
    persons face
  • Murphy Zajonc similar study using Chinese
    characters found similar results
  • e. Studies disproving subliminal perception
  • The Canadian Brodcasting Corp. participated in a
    study that flashed a message 352 times during a
    TV show. Then asked people to call in and guess
    the message. None did. The message was
    Telephone Now! - there was no increase in phone
    usage after the messages

22
Difference Threshold
  • a. Difference threshold (aka Just-noticeable-diff
    erence) the minimum difference that a person
    can detect between two stimuli
  • b. First studied by Ernst Heinrich Weber
  • c. Webers Law the principle that, to perceive
    their difference, two stimuli must differ by a
    constant minimum percentage

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Sensory Adaptation
  • 1. Sensory adaptation diminished sensitivity
    as a consequence of constant stimulation
  • After constant exposure to a stimulus, our nerve
    cells fire less frequently
  • 2. For example
  • a. We often stop noticing our own cologne or
    perfume
  • b. We ignore the repetitive noises around us
  • c. We ignore the feeling of glasses on our face
  • So if we stare at a point long enough, what would
    happen? Would sensory adaptation occur and the
    point disappear?

25
  • Get out a piece of white paper!

26
  • Stare directly at the center for 1 minute!

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  • Stare directly at the center dot for 1 minute!

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Have Fun!
  • http//www.illusions.org/

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VISION
  • How does our body construct our conscious visual
    experience? How do we transform particles of
    light energy into colorful sights?

33
Vision
  • A. Stimulus Input
  • 1. Transduction
  • a. conversion of one form of energy into another
  • b. In sensation, the transforming of stimulus
    energies into neural impulses
  • 2. The three psychological properties of light
  • a. Wavelength the distance from the peak of
    one light or sound wave to the peak of the next

34
  • b. Hue the dimension of color that is
    determined by the wavelength of light
  • long wave lengths reddish colors
  • short wave lengths bluish colors
  • c. Amplitude the height of a wave measured
    from the trough to the peak
  • d. Intensity the amount of energy in a light
    or sound wave which we measure as brightness or
    loudness
  • great amplitude bright colors loud sounds
  • low amplitude dull colors soft sounds
  • e. Saturation how pure the light or sound is,
    for example reddish-orange and blue-green are
    less pure

35
  • B. The Human Eye
  • 1. The parts of the eye
  • a. Cornea a transparent protector covering the
    eye
  • b. Iris
  • a ring of muscle tissue that forms the colored
    portion of the eye around the pupil
  • and controls the size of the pupil opening
  • c. Pupil the adjustable opening in the center
    of the eye through which light enters
  • d. Lens the transparent structure behind the
    pupil that changes shape to focus images on the
    retina

36
  • 2. Basic Visual Processes
  • a. Accommodation the process by which the
    eyes lens changes shape to focus the image of
    near objects on the retina
  • b. The Retina
  • the light sensitive inner surface of the eye,
  • containing the receptor rods and cones plus
    layers of neurons that begin the processing of
    visual information.
  • c. Fovea the central focal point in the
    retina, around which the eyes cones cluster

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  • d. Nearsightedness a condition in which nearby
    objects are seen more clearly than distant
    objects because the lens focuses the image of
    distant objects in front of the retina

39
  • e. Farsightedness a condition in which faraway
    objects are seen more clearly than near objects
    because the image of near objects is focused
    behind the retina

40
  • 3. The retina
  • a. Rods
  • retinal receptors that detect black, white, and
    gray
  • necessary for peripheral and twilight vision,
    when cones do not respond
  • b. Cones
  • receptor cells that are concentrated near the
    center of the retina and that function in
    daylight or in well-lit conditions
  • the cones detect fine detail and give rise to
    color sensations


Remember This
41
  • c. The pathway of light enters through the
    pupil, lens focuses it on retina
  • Light strikes the rods and cones at the back of
    the retina then moves forward to the bipolar
    cells and the ganglion cells.
  • The ganglion cells formed the optic nerve which
    carries info to the thalamus.
  • The optic nerve can send nearly 1 million
    messages at once.

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  • d. The blind spot the point at which the optic
    nerve leaves the eye, creating a blind spot
    because no receptor cells are located there

44
  • C. Feature Detection- nerve cells in the brain
    that respond to specific features of the
    stimulus, such as shape, angle or movement.
  • Detectors in the visual cortex pass info to other
    areas of the brain in order to response.
  • Ex Face Recognition occurs in the temporal lobe
    just behind the right ear.

45
  • D. Visual Processing Parallel processing
  • 1. Parallel processing
  • a. The processing of several aspects of a
    problem simultaneously
  • b. The brains natural mode of information
    processing for many functions, including vision
  • The brain divides a visual scene into sub
    dimensions such as color, movement, form, and
    depth. We then construct our perceptions by
    integrating the separate but parallel work of the
    different visual teams.

46
  • 2. Examples
  • a. Blindsight the ability to respond to
    something not consciously perceived
  • b. Visual agnosia an inability to recognize
    objects despite otherwise satisfactory vision.
  • c. Prosopagnosia ability to recognize objects
    but not faces

47
What percentage of the electromagnetic spectrum
can humans see?
48
  • E. Visual Information Processing Color Vision
  • 1. Subtractive and additive color mixing
  • a. Subtractive color mixing is the process we
    are familiar with in which we mix blue and yellow
    and get green. It is subtractive because you are
    subtracting the number of wavelengths that are
    reflected

49
  • b. Additive color mixing is the process of
    mixing wavelengths of light
  • The primary colors are therefore Red, Green and
    Blue
  • It was from this information that the first
    theories of color vision were developed.

50
  • 2. Young-Helmoltz/Trichromatic Theory
  • a. The theory that the retina contains three
    different color receptors
  • b. One most sensitive to red, one to green, one
    to blue
  • c. Which when stimulated in combination can
    produce the perception of any color

51
  • d. Color blindness not actually blind but they
    lack the proper receptors for red or green
  • Lack of functioning cones
  • e. Problems with the theory
  • Why is it that people who are color blind for red
    are also color blind for green. Yet they see
    yellow fine which is produced by combining red
    wavelengths with green wavelengths
  • After images when you stare at a green square
    for a while and look at a white sheet of paper
    you see red, greens opponent color.

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  • 3. The Hering Opponent Process Theory
  • a. The theory that opposing retinal process
    (red-green, yellow- blue, white - black) enable
    color vision
  • b. For example, some cells are stimulated by
    green and inhibited by red others are stimulated
    by red and inhibited by green
  • c. Color Constancy a problem for the Opponent
    Process Theory
  • perceiving familiar objects as having consistent
    color, even if changing illumination alters the
    wavelengths reflected by the object

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  • If you put on green tinted glasses you still see
    objects as the correct color. Your brain
    subtracts the green from the object and sees the
    true color
  • 4. The Retinex Theory
  • a. A combination of the words retina and cortex
  • b. When information from various parts of the
    retina reaches the cortex, the cortex compares
    the inputs to determine the brightness and color
    perception for each area

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  • c. Feature Detectors nerve cells in the brain
    that respond to specific features of the
    stimulus, such as shape, angle or movement
  • Hubel and Wiesel found that various receptor
    cells respond maximally to a bar flashed at a
    particular angle.
  • They identified three different types of cells in
    the visual cortex, Simple Cells, Complex
    cells,and hyper complex or End-stopped cells

62
  • C. Visual Information Processing Feature
    Detection
  • 1. Some basic terms
  • a. Visual Field the whole area of the world
    that you can see at any time. Divided into left
    and right visual fields
  • b. Receptive Field the part of the visual
    field to which any one neuron responds

63
The Auditory Sense
64
How do we hear?
  • Draw a bow across a violin and the resulting
    stimulus energy is sound waves- molecules of air,
    each bumping into the next. Our ears detect these
    brief air pressure changes. The ears then
    transforms the vibrating air into nerve impulses,
    which our brain decodes as sound.

65
Sound
  • A. The Auditory Stimulus
  • 1. Audition the sense of hearing
  • 2. Sound is caused by vibrations of air
    molecules
  • 3. Three psychological properties of sound
  • a. Frequency the number of complete
    wavelengths that pass a point in a given time
  • b. Pitch a tones highness or lowness depends
    on frequency
  • c. Loudness is determined by the amplitude of
    the sound wave. Loudness is measured in
    decibels.

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  • B. The Human Ear and Transduction
  • 1. The outer ear- channels sound waves through
    the auditory canal to the eardrum.
  • Eardrum- tight membrane that vibrates with waves

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  • 2. The middle ear the chamber between the
    eardrum and cochlea containing three tiny bones
    (hammer, anvil, stirrup) that concentrate the
    vibrations of the eardrum on the cochleas oval
    window

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  • 3. Inner ear the innermost part of the ear
    containing the cochlea, basilar membrane and hair
    cells.
  • a. The cochlea a coiled, bony fluid- filled
    tube in the inner ear through which sound waves
    trigger nerve impulses
  • b. The basilar membrane a membrane inside the
    cochlea that is lined with hair cells
  • c. The hair cells (around 16,000) vibrate
    sending a signal to the auditory nerve

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  • Incoming vibrations cause the cochleas membrane
    (oval window) to vibrate, jostling the fluid that
    fills the cochlea tube.

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  • While the tube fills with fluid, this motion
    causes ripples in the basilar membrane, bending
    hair cells lining its surface.
  • Hair cell movement triggers impulses in the
    adjacent nerve cells, whose axons converge to
    form the auditory nerve
  • This sends neural messages to the thalamus then
    to the temporal lobe for
  • processing.

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  • C. Theories of Hearing
  • 1. Loudness is perceived by the number of hair
    cells that respond
  • 2. Pitch
  • a. The Place theory in hearing, the
  • theory that links the pitch we hear with
  • the place where the cochleas
  • membrane is stimulated
  • explains how we hear high pitched sounds
  • but fails to show how we hear low pitched sounds

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  • b. The frequency theory in hearing, the theory
    that the rate of nerve impulses traveling up the
    auditory nerve matches the frequency of a tone,
    thus enabling us to sense its pitch
  • explains how we hear low pitched sounds
  • but fails to explain how we hear high pitched
    sounds
  • c. Most likely a combination of the two combines
    to explain how we hear different pitches

74
  • d. The Volley Principle shows how when hair
    cells fire in alternating patterns we can hear
    sounds that have frequencies above 1000 times per
    second
  • 3. Determining the location of a sound
  • a. Having two ears allows us to locate the
    source of a sound
  • b. Our auditory system is extremely sensitive to
    how intense and when a sound arrives

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  • D. Hearing Loss
  • 1. Conduction deafness hearing loss caused by
    damage to the mechanical system that conducts
    sound waves to the cochlea
  • 2. Sensorineural or nerve deafness hearing
    loss caused by damage to the cochleas receptor
    cells or to the auditory nerves
  • 3. Deaf advocates disagree with the use of
    cochlear implants for children born deaf. They
    reason that deafness is NOT a disability.

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Hearing through bone conduction
  • When you plug your ears and listen to yourself
    speak, you hear both the sound conducted by air
    waves to the outer ear and that carried directly
    to the auditory nerve by bone conduction.
  • Bone conduction demonstration.

77
Hearing through bone conduction
  • People who are deaf due to a defect in the inner
    or middle ear will still be able to hear by bone
    conduction.
  • Beethoven, could still hear his piano by placing
    one end of his walking stick against it and
    gripping the other end between his teeth.

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  • How well can you hear?

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  • D. The Organ of Corti are neurons activated by
    the hair cells vibrating

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V. The Other Senses
  • A. Touch Four skin senses - warm, cold,
    pressure and pain
  • 1. Pain
  • a. Phantom Limb sensations indicate that with
    pain, the brain can misinterpret the spontaneous
    central nervous system activity
  • b. Rubber-hand illusion
  • c. Gate Control theory
  • The theory that the spinal cord contains a
    neurological gate that blocks pain signals or
    allows them to pass on to the brain

82
  • The gate is opened by activity of pain signals
    traveling up small nerve fibers and is closed by
    activity in large fibers by information coming
    from the brain
  • d. Pain control
  • Lamaze method of pain control operates by using
    relaxation, counter-stimulation and distraction
  • Simple distraction alone also seems to work in
    easing the pain of many medical procedures.

Virtual reality being used to distract a burn
patient
83
  • 2. Temperature
  • a. We have receptors for warm and cold
  • b. The sensation of hot is created by
    simultaneous excitement of both warm and cold
    receptors

84
  • C. Body senses
  • 1. Kinesthesis(proprioception) the system for
    sensing the body position and movement of
    individual body parts
  • Ian Waterman

85
  • B. The Chemical Senses
  • 1. Taste Five basic sensations
  • a. Sweet, sour, salty, umami, and bitter
  • b. Taste buds are replaced throughout our lives
  • c. We have less taste buds as we get older
  • d. Sensory interaction the principle that one
    sense may influence another, as when the smell of
    food influences the taste

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  • 2. Smell or olfaction
  • a. Like taste smell is a chemical sense
  • b. Receptor cells pick up different chemical
    compositions
  • c. 1 of our genes are used to develop the many
    different smell receptors in our nose

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Bell-ringer 1
  • Write 3 M/C questions on the material we have
    already covered. Make one for each of the
    following concepts
  • 1. General Sensation
  • 2. Vision
  • 3. Audition

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  • 3. Pressure
  • a. We can feel very minor points of pressure
  • b. Pressure is sensed through specialized
    receptor cells known as pancinian corpuscles

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  • 3. Vestibular sense the sense of body movement
    and position including the sense of balance
  • 4 Sensory Restriction
  • a. Includes loss of a sense such as sight,
    resulting in increased perception in other senses
  • b. Also includes sensory monotony - like that of
    a prisoner in solitary confinement
  • c. Has been used in therapeutic models
  • REST Restricted environmental stimulation
    therapy
  • Has worked well with smokers who want to quit

92
  • Copy the phrase below and then provide the
    punctuation that would make it a meaningful
    sentence.
  • TIME FLIES I CANT THEYRE TOO FAST

93
VI. Perception
  • A. Selective Attention
  • 1. Selective Attention the focusing of
    conscious awareness on a particular stimulus, as
    in the cocktail party effect
  • 2. The cocktail party effect the ability to
    attend selectively to only one voice among many

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  • Inattentional blindness a form of selective
    attention in which we are focused in on one thing
    that we miss obvious things in front of us
  • Changed Blindness a form of selective attention
    in which we are focused in on one thing that we
    do not notice changes in front of us

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Do you see circles with white lines or a cube.
Notice how the x moves from front to back
96
Bell Ringer 2
  • Draw a picture that describes the scene below.
  • You are seated on the beach of a tropical island.
    In front of you several palm trees sway in the
    breeze. Young children can be seen playing in
    the sand at the shore line while older children
    and adults are splashing in the water. A
    windsurfer glides by on the calm water while a
    cruise ship sits off in the distance waiting to
    enter port. Add one other object of your choice
    that would be near to you and one that you can
    see in the distance.

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  • 3. The Ulric Neisser Basketball experiment
  • a. Subjects shown a video of two three man teams
    passing a basketball
  • b. Asked to count the number of times black
    shirted B-ball players passed the balls
  • c. Half way through the video a woman with a red
    umbrella walked through the scene
  • d. Most subjects failed to notice the woman

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  • B. Perceptual Illusions
  • 1. The Muller-Lyer Illusion created in 1889 uses
    two lines with arrows pointing in or out. The
    carpentered world phenomenon comes into play here
    as this illusion does not work well with people
    who do not live in a square world.

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  • 2. The Distorted Room illusion works by changing
    the angles of the room, the images in the room
    and the distance from the viewer.

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Optical Illusion Web Sites
  • Click to visit these sites

Color Cube.com
Just Riddles
NIEHS Kids Pages
Paintings
Brainbashers
Moillusions
Lightisreal.com
Optillusions.com
102
More Illusions
Allpsych.com
Meltingpot
Premier photographer
Psycharts
MIT
Amazing Brain
Optical Illusions UK
Exploratorium
123opticalillusions
Bristol
Eye magic
Omnibrain
103
Echalk
Optillusions.com
lycos
Optillusions.com
Info about Opt Illusions
Optillusions.com
Optillusions.com
Optillusions.com
Optillusions.com
Optillusions.com
Optillusions.com
104
  • Try to count the black dots

105
  • C. Perceptual Organization
  • 1. Gestalt
  • a. an organized whole
  • b. Gestalt psychologists emphasize our tendency
    to integrate pieces of information into
    meaningful wholes
  • c. can be summarized by the statement the whole
    is greater than the sum of its parts
  • d. The Law of Pragnanz states that we tend to
    see things in their simplest form.

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  • 2. Form perception
  • a. Figure Ground Relationships the
    organization of the visual field into objects
    (the figures) that stand out from their
    surroundings (the ground

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  • b. Grouping the perceptual tendency to
    organize stimuli into coherent groups
  • Similarity figures similar to each other we
    group together
  • Proximity we group nearby figures together.
  • Closure we fill in gaps to create a complete,
    whole object
  • Continuity We perceive smooth, continuous
    patterns rather than discontinuous ones

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Grouping
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  • 3. Depth Perception
  • a. Depth perception the ability to see objects
    in three dimensions although the images that
    strike the retina are two-dimensional allows us
    to judge distance
  • b. Visual cliff a laboratory device for
    testing depth perception in infants and young
    animals

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  • c. The Gibson and Walk study involved placing 6
    to 14month old babies on the edge of a safe
    canyon (a visual cliff). Their mothers then
    tried to convince the infant to cross the chasm.
    Most of the babies refused to crawl across.
    Newborn animals show similar results.

113
  • d. Binocular cues depth cues such as retinal
    disparity and convergence that depend on the use
    of two eyes
  • retinal disparity a binocular cue for depth.
    The fact that each eye sees a slightly different
    picture. The brain combines the two and this
    provides a clue as to how far away an object is

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Stereogram -
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  • convergence a binocular cue for depth the
    extent to which the eyes converge inward when
    looking at an object. The closer the object the
    greater convergence
  • e. Monocular Cues distance cues such as linear
    perspective and overlap, available to either eye
    alone
  • interposition if one object blocks another we
    perceive it as closer
  • Relative Size if we assume that two objects are
    similar in size, we see the smaller one as being
    farther away

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  • Aerial Haze hazy objects seem farther away
  • texture gradient a change from coarse, distinct
    features to fine indistinct features. Up close
    you see individual blades of grass, while you see
    a field of green farther away
  • Relative height objects higher in our field of
    vision seem to be farther away
  • Linear perspective parallel lines seem to
    converge as distance increases

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  • 4. Motion Perception
  • a. Without motion perception we would be unable
    to do many of our everyday activities
  • b. Phi phenomenon when two or more adjacent
    lights blink on and off in succession they will
    appear as one moving light.
  • c. Stroboscopic movement when still pictures
    are presented in rapid succession an illusion of
    movement is created.
  • d. Autokinetic effect if a dot of light is
    projected onto a screen in a dark room it will
    appear to move

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  • 5. . Perceptual Constancy
  • a. Perceptual constancy perceiving objects as
    unchanging even as illumination and retinal
    images change.
  • b. Size Constancy we perceive objects as being
    the same size even though they are far away
    a.k.a. Emmerts Law
  • c. Shape Constancy the fact that as the angle
    an object is presented from changes our
    interpretation of its shape stays constant

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Size and distance
125
VII. Perceptual Interpretation
  • A. Perceptual Adaptation
  • 1. the ability to adjust to an artificially
    displaced or even inverted visual field.
  • 2. For example students with upside down vision
    goggles will eventually adapt.
  • B. Perceptual Set
  • 1. A mental predisposition to perceive one thing
    and not another.

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  • Schemas are concepts that help us mentally
    organize our world.

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VIII. ESP
  • A. ESP The controversial claim that perception
    can occur apart from sensory input. Said to
    include telepathy clairvoyance and precognition
  • B. Parapsychology the study of paranormal
    phenomena including ESP and psychokinetic powers.

129
Bell-ringer 2
  • Without using your book, give me your best guess
    at to how we
  • See color
  • Hear different pitches of sound

130
Bell-ringer 3
  • Describe the two competing theories of color
    vision.
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