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How does the world out there get in? How do we construct our representations of the outside world? SENSATION

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PAIN PERCEPTION There is no one stimulus that causes pain and there is often other sensations ... our nerve cells fire less frequently. Ex: smell in a room ... – PowerPoint PPT presentation

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Title: How does the world out there get in? How do we construct our representations of the outside world? SENSATION


1
How does the world out there get in?How do we
construct our representations of the outside
world?SENSATION PERCEPTION
  •  

2
SENSATION PERCEPTION
  • SENSATION VS. PERCEPTION
  • TOP-DOWN VS. BOTTOM-UP PROCESSING

3
SENSATION PERCEPTION
  • SENSATION The detecting of physical energy from
    the environment and the encoding of it as neural
    signals.
  • PERCEPTION The selecting, organizing, and
    interpreting of our sensations.
  •  Sensory analysis starting at the entry level
    (sensory organ) is know as bottom-up processing.
    Top-down processing is creating meaning beginning
    with our experiences and expectations.

4
  • http//www.firstpeople.us/pictures/art/odd-sizes/l
    s/The-Forest-Has-Eyes-800x409.html
  • Bev Doolittle painting
  • Bottom-up processing is seeing color, lines, etc.
  • Top-down processing involves consideration of the
    title The Forest Has Eyes and finding deeper
    meaning in the picture.

5
MEASURING SENSATION
  • ABSOLUTE THRESHOLD
  • DIFFERENCE THRESHOLD

6
THRESHOLDThe point of detecting stimuli
  • Absolute threshold the minimum stimulation
    necessary to detect a particular stimulus (light,
    sound, pressure, taste, odor). Established at a
    50 detection rate. This depends not only on the
    signals strength but also our psychological
    state. (ex parents of a newborn vs. siblings of
    a newborn, sentry during wartime vs. one during
    peace time)

7
SIGNAL DETECTION THEORY
8
SIGNAL DETECTION THEORY
  • Signal detection theory PREDICTS when we will
    detect weak signals, measured as our ratio of
    hits to false alarms.
  • Signal detection theorists seek to understand why
    people respond differently to the same stimuli,
    and why the same persons reactions may differ
    under different circumstances.
  • Signal detection can have life or death
    consequencesthink about all of the studies
    having been done regarding talking/texting while
    driving

9
SIGNAL DETECTION THEORY
  • Studies show that peoples vigilance diminishes
    after about 30 minutes of judging a faint signal,
    but this varies according to time of day, the
    type of task, and whether the observer
    periodically exercises. (This information has
    significant impact on security situationsairports
    , military bases, etc.)

10
Other Sensory Constructs(When math physics
meet psychology!)
  • Difference threshold minimum difference a
    person can detect between any two stimuli. Also
    known as just noticeable difference (JND). The
    magnitude of the increase its proportional
    relationship to the starting signal is relevant.
  • 100g 10g detection, 1kg 10g no
    detection. Webers law regardless of two
    stimuli magnitude, they must differ by a constant
    proportion for the difference to be perceptible.
    (Light difference by 8, weight by 2, and sound
    by 0.3.) Related to Fechners law and
    Weber-Fechner law.

11
OTHER SENSORY EXPERIENCES
  • SENSORY ADAPTATION
  • HABITUATION

12
Other Sensory Constructs
  • Sensory adaptation diminishing sensitivity to
    an unchanging stimulus. After constant exposure
    to a stimuli, our nerve cells fire less
    frequently. Ex smell in a room, hot shower,
    cold pool If our eyes were not in constant
    motion, we would lose sight of images. (Thats
    why we perceive motion when there is none
    sometimes.) The beauty of this is that it allows
    us to attend to informative changes in our
    environment and to not be distracted by the
    uninformative. Once you have adapted you cant
    return to your original state of sensitivity.
  • Habituation the weakening of a response to a
    stimulus, or the diminished effectiveness of a
    stimulus, following repeat exposure to the
    stimulus. You can return to original sensitive
    by consciously redirecting your attention. For
    example, if I tell you to listen to the air
    coming out of the vent, you can hear at any point
    you so choose.

13
FUNDAMENTAL LESSON IN SENSATION AND PERCEPTION
  • The fact that our sensory receptors are alert to
    novelty and if bored with repetition, free our
    minds to attend to different things meansWe
    perceive the world not as it exactly is but as it
    is useful for us to perceive it!
  • Our perception is our reality!

14
TRANSDUCTION
15
THE SENSES
  • We look with our eyes but we see with our brains.
  • We can say the same about hearing, smelling,
    tasting, etc.
  • TRANSDUCTION the transforming of physical
    stimuli into neural impulses for our brains to
    interpret

16
Note guide instructions
  • Identify basic structures of the primarily organ
    and pathway of the signal from stimulus to brain.
  • Identify where transduction occurs
  • Identify basic malfunctions of the system

17
VISION
  • WAVELENGTH
  • AMPLITUDE
  • TRANSDUCTION
  • RETINA RODS CONES

18
THE EYE, VISION
  • http//library.thinkquest.org/26111/howitworks1.ht
    ml
  • Vision visible light component of the EM
    spectrum. Wavelength gives us hue (blue, green,
    etc.) and amplitude (a measure of energy) gives
    us brightness.
  • Cool fact The retina is actually a piece of
    the brain that migrates to the eye during fetal
    development! Therefore the retina encodes and
    processes some of the information as well as
    passes on neural impulses.
  • Cones color rods brightness/dimness

19
Through the eye to the brain
  • Cornea gt pupil gt lens gt fluid gt retina
    (consisting of rods cones)
  • Rods and cones of the retina convert energy into
    electrical impulse (transduction) fovea area
    of high cone concentration
  • The eye contains 91 million rods but only 4.5
    million cones.

20
Through the eye to the brain
  • Rods/cones gt bipolar cells gt ganglion cells gt
    optic nerve (where it attaches to the retina,
    there are no receptors creating your blind spot)
    gt thalamus gt occipital lobe

21
Vision Experiment
  • Shift your eyes to the left and close them.
  • Gently rub the right side of your eye lid.
  • Do you see the light image?
  • Where do you see this light?
  • Why does this happen?
  • The receptors in your eye are so sensitive that
    they respond to touch but the signal is
    interpreted as light. You see the light to the
    left because your brain reads the signal as light
    coming from the left hand side since that is what
    would normally stimulate the cells on the right
    side of your retina.

22
Sensory Adaptation Vision
  • Our eyes are in constant motion to prevent
    sensory adaption (loss of sensation due to
    redundant stimuli) of our vision.
  • These movements are called saccades. They are
    controlled by the cerebellum the frontal lobe.
    (Finger to nose test)
  • Lingering images in our brain often create
    illusions of movement once our eyes have moved on
    to a new target.

23
Vision Disorders
  • Near-sightedness
  • Far-sightedness

24
Vision Disorders
  • Color blindness
  • Visual Agnosia (literally lack of knowledge
    describes someone who can not identify objects
    visual. May be able to describe.

http//www.colourblindawareness.org/colour-blindne
ss/types-of-colour-blindness/
25
Parallel Processing
  • The taking in and processing of various sensory
    information simultaneously.
  • Example Visually we see color, depth, movement,
    and form and process this information all at the
    same time.
  • Example When a song we like comes on the radio
    we will sing the words, drum our fingers to the
    beat, and process emotional responses all at the
    same time.

26
Seeing Color
  • Color color is the brains interpretation of
    reflected wavelengths of light. The eyes
    receptors (aka cones) are designed to see red,
    blue, and green light which when alternately
    stimulated will allow for the seeing of different
    colors.
  • -Young-Helmholtz trichromatic theory (red, blue,
    green)

27
Negative Afterimages
  • -Opponent-process theory http//www.exploratorium.
    edu/exhibits/bird_in_a_cage/bird_in_a_cage.html
  • Our vision system is an opponent (opposites)
    processing system. When one receptor site is
    exhausted from overuse, the other will kick in to
    high gear when given the opportunity.

28
Color Constancy
  • Ability to recognize
  • color of an object
  • despite changes in
  • lighting.

29
SHAPE CONSTANCY
  • We still perceive the
  • door as a rectangle even
  • though if we were to draw
  • this it would be a trapezoid.

30
Auditory Sense (Hearing)
  • So, if a tree falls in the forest, and no one is
    around to hear it, does it make a sound?

31
THE EAR
  • http//www.cpo.com/ca/downloads/18_420human20ear
    20diagram.pdf
  • Hearing the conversion of air pressure waves
    into neural messages that are interpreted as
    sound
  •   http//www.freehearingtest.com/core.shtml
  • We hear sounds best within the range of the human
    voice. We are also highly sensitive to faint
    sounds and skilled at distinguishing from many
    similar sounds such as voices.

32
HEARING, AUDITORY
  • Mechanics the amplitude (energy) of the wave
    determines its loudness and the frequency of the
    wave determines its pitch. Prolonged exposure to
    sounds above 80-85 decibels can lead to hearing
    loss.
  • General rule If you cannot talk over a noise,
    it is potentially harmful to your hearing.
    Experiencing ringing after exposure is a sign of
    damage.

33
THE EAR
  • Outer ear (ear canal to eardrum) gt middle ear
    (bones hammer, anvil, stirrup gt oval window gt
    inner ear (cochlea, basilar membrane, and hair
    cells )gt auditory nerve gt thalamus gt temporal
    lobe

34
Hearing Loss/Disruptions
  • Tinnitus ringing or sounds in the ear with no
    external source
  • http//www.healthline.com/adamcontent/tinnitus?utm
    _mediumaskutm_sourcesmartutm_campaignarticle
    utm_termTinnitusask_returnTinnitus
  • Sensorineural hearing loss (nerve deafness)
    Loss of hearing due to age, heredity, and
    prolonged exposure to loud sounds. Hair cells
    are damaged and cannot repair themselves. In
    severe instances cochlear implants can be used to
    restore hearing.

35
Cochlear Implant
36
Hearing Loss/Disruptions
  • Conduction hearing loss Problems with the
    mechanical system (outer ear/middle ear) that
    result in the conduction of the sound waves. A
    punctured eardrum or damage to the tiny bones of
    the middle ear can result in this.
  • A hearing aid, which amplifies sound, can help
    with this type of hearing loss.

37
More on sounds hearing
  • Study People who live with continual noise in
    factories, in homes near airports, and in
    apartments near trains and highways suffer
    elevated rates of stress-related disorders high
    blood pressure, anxiety, and feelings of
    helplessnessconfounding variables??? Evans, et
    al, 1995

38
How we hear
  • Placement of the ears allows us to detect
    location of sounds easily. Remember our click
    lab? When were people most likely to make a
    mistake?

39
How we hear
  • Place theory The idea that we detect different
    pitches because different sound waves trigger
    activity at different places along the cochleas
    basilar membrane.
  • Frequency theory the rate of
  • nerve impulses traveling up the
  • auditory nerve matches the frequency of the tone,
    allowing us to determine pitch.

40
TASTE, GUSTATORY SENSE
  • Taste buds (which are essentially modified skin
    cells) are located in the papillae (bumps of the
    tongue) and each one has roughly 50 receptor
    cells.

41
TASTE, GUSTATORY SENSE
  • Four Five basics sensations sweet, sour, salty,
    bitter, and umami (meaty taste, MSG). Taste
    receptors reproduce themselves but the amount you
    have declines with age. Smoking alcohol
    accelerate the decline. Receptors exist in the
    back and on the roof of the mouth, too.
  • Smelling a foods aroma will enhance the taste.
    Therefore, food doesnt seem as flavorful when we
    have a cold. This is known as sensory
    interaction.
  • Smell texture taste flavor.

42
Taste buds/papillae
43
SMELL, OLFACTORY SENSE
  • Olfactory cells line the olfactory epithelium
    of the nasal passage.
  • Like taste, smell is a chemical sense. Sense
    peaks at early adulthood, and women typically
    have a heightened sense compared to men. Smell
    is also acutely attached to memories, especially
    good scents to good memories.

44
SMELL, OLFACTORY SENSE
  • Head trauma is the 1 cause of people losing
    their sense of smell.
  • Olfactory receptors gtgt olfactory bulb gtgt cerebral
    cortex gtgt hippocampus, amygdala, and
    hypothalamus.

45
SYNESTHESIA
  • Synesthesia occurs when one
  • sort of sensation produces
  • another, for example,
  • tasting a color or
  • hearing a number.

46
TOUCH, TACTILE SENSE
  • Touch is a combination of at least 4 distinct
    skin sensations pressure, warmth, cold, and
    pain.
  • Other skin sensations are variations of the basic
    4 mentioned above. For example stroking
    adjacent pressure spots creates tickle.
  • Repeated gentle stroking of a pain spot creates
    an itching sensation.
  • Skin with no hair (palms of hands, soles of feet
    are more sensitive)

47
Homunculus An illustration of the body if it
represented how much of the sensory cortex was
dedicated to that parts sense of touch.
48
TOUCH, TACTILE SENSE
  • Touch sensations involve more than tactile
    stimulations, hence you cannot tickle yourself
    easilytop-down processing plays a role. Also,
    our brain knows to be sensitive to surprise
    attacks! (hand illusion video)
  • http//www.youtube.com/watch?vsxwn1w7MJvk

49
PAIN PERCEPTION
  • Pain is the bodys way of telling you something
    is wrong. It tells you to change your behavior
    immediately.
  • Pain is a property of the sensory neurons in the
    region and the brain as well. Pain has been
    documented in body parts that dont exist in the
    case of amputees. (Phantom sensations have been
    documented with all of the senses.)
  • There are also cases of people who do not sense
    pain or are not bothered by it.

50
PAIN PERCEPTION
  • There is no one stimulus that causes pain and
    there is often other sensations that go along
    with pain.
  • Substance P is the neurotransmitter that relays
    messages of pain. Endorphins inhibit these
    signals.

51
PAIN PERCEPTION
  • Pain can also be turned on and turned off by
    distractions, relaxation, drugs, endorphins,
    other stimuli like ice, electrical impulses or
    acupuncture.
  • Gate-control theory theory that other messages
    from the brain or the body can close the gates
    for pain messages.

52
VESTIBULAR SYSTEM BALANCE/EQUILIBRIUM
  • Balance/equilibrium Within the inner ear, in
    the semicircular canals, connected to the cochlea
    by the vestibular sacs, contain fluids that move
    when the head moves. This stimulates hair-like
    receptors sending messages to our brain about our
    position and balance.
  • Messages are also sent to your eyes to assist you
    in focusing on a target.
  • Since the fluids dont stop moving as quickly as
    you do, this leads to a dizzy sensation following
    spinning in a circle.

53
VESTIBULAR SYSTEM BALANCE/EQUILIBRIUM
54
KINESTHESIS WHERE ARE MY FEET?
  • Kinesthesis is our sense of body parts position
    and movement through sensors all of our body in
    muscles, tendons, and joints. Loss of this
    sensation leads to a sense of disembodiment.
  • Remember the finger to nose test? You can do
    this almost as easily with your eyes closed due
    to KINESTHESIS!

55
PERCEPTION
  • PERCEPTION The selecting, organizing, and
    interpreting of our sensations.
  • Selective attention at any moment our awareness
    focuses on only a limited aspect of all that we
    experienceby one estimate, our collective senses
    take in 11,000,000 bits of information per
    second, of which we consciously process about 40.
  • Cocktail party effect
  • When vision competes with other senses, it
    usually wins, this is known as visual capture.
    (Boomerang cartoon voices.)
  • http//www.youtube.com/watch?vvJG698U2Mvo

56
PERCEPTION
  • INATTENTIONAL BLINDNESS The inability to
    see/notice things due to attention being
    redirected. (Think about the gorilla test!)
  • When distracted, either our sensory system is not
    activated or our perception system is not
    activated making it impossible to detect the
    stimulus.

57
Perceptual Organization GESTALT
  • German for whole or form
  • In perception the whole may exceed the sum of its
    parts.
  • It describes how we organize our sensations into
    perceptions
  • http//www.at-bristol.org.uk/Optical/NeckerCube_ma
    in.htm
  • http//graphicdesign.spokanefalls.edu/tutorials/pr
    ocess/gestaltprinciples/gestaltprinc.htm
  • www.thepsychfiles.com

58
Perceptual Organization GESTALT
  • To make sense of our world, our brain is built to
    organize the information automatically.
  • Gestalt principles of CLOSURE, PROXIMITY,
    SIMILARITY, CONTINUITY, etc. can all be used to
    explain ambiguous stimuli

59
Figure-Ground
  • http//www.lewport.wnyric.org/JWANAMAKER/illusions
    _plus/illusions_figureground.htm
  • Stereogram, 3-D
  • http//www.netaxs.com/mhmyers/rdsjpgs/eagle.jpg

60
PERCEPTUAL SET
  • A mental predisposition that influences what we
    see. (Police prepped for violence.)
  • Once we have formed the wrong idea about reality
    it is difficult to see the truth
  • Loch Ness monster, UFOs, man in the moon, Jesus
    on toastits not just what we see or hear, but
    what our minds eye perceives.
  • Where does our perceptual set come from schemas
    and accommodation and assimilation

61
Visual Cues Depth Perception
  • Monocular cues vs.
  • Binocular cues Cues that can
  • be detected with one
  • eye vs. cues that can be detect
  • ed with 2 eyes. Helping us to determine
    distance/depth.

62
BINOCULAR (2 EYES) CUES
  • Because our eyes are only about 2.5 inches apart,
    our retinas receive slightly different images.
    The brain compares these and the difference
    between is called retinal disparity. Our brain
    interprets this as relative distance.
  • Finger sausage experiment
  • 3-D movies are made with 2 separate cameras that
    exaggerate retinal disparity.

63
MONOCULAR (1 EYE) CUES
  • Activity Draw a traditional picture of a
    landscape. Something simple and similar to what
    you would have done in elementary school
    Include a horizon (straight or hilly), a house in
    the distance and a house close up. A couple of
    tress, maybe some shrubs or flowers. Include
    clouds, maybe some birds and the sun.

64
MONOCULAR (1 EYE) CUES
  • Relative height things higher in our field of
    vision are perceived as farther away.
  • Relative size the smaller image is perceived as
    farther away.
  • Interposition If an object partially blocks our
    view we perceive it as closer.
  • Linear perspective parallel lines that appear
    to converge with distance.
  • Light and shadow also help us see depth. Think
    of drawing a sphere vs. a circle.

65
Words to Know
  • Schema a concept or framework that organizes
    and interprets information ex Erin knows what
    dogs are because we have two.
  • Assimilation interpreting ones new experience
    in terms of ones existing schemas Ex Erin saw
    horses for the first time this weekend, she
    called them dogs.
  • Accommodation adapting ones current
    understandings (schemas) to incorporate new
    information Ex Erins understanding of
    domesticated animals will eventually include
    separate categories for dogs and horses.
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