Sensation

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Sensation Perception
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The Forest Has Eyes Bev Doolittle
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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

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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

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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

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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

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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.

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Change Blindness

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

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• 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.

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

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• 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

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

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Sensing the World
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• 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.

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• 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

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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?

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• Get out a piece of white paper!

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• 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?

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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

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• 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

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• 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

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• 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

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• 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

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• 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

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• 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

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• 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.

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• 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.

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• 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

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What percentage of the electromagnetic spectrum
can humans see?
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• 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

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• 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.

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• 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

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• 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

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• 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

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The Auditory Sense
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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.

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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

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• 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.

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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

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• 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
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• 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

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

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• 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

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

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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
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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
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More Illusions
Allpsych.com
Meltingpot
Premier photographer
Psycharts
MIT
Amazing Brain
Optical Illusions UK
Exploratorium
123opticalillusions
Bristol
Eye magic
Omnibrain
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Echalk
Optillusions.com
lycos
Optillusions.com
Info about Opt Illusions
Optillusions.com
Optillusions.com
Optillusions.com
Optillusions.com
Optillusions.com
Optillusions.com
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• Try to count the black dots

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• 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.

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• 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
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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.

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Bell-ringer 2

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

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Bell-ringer 3

• Describe the two competing theories of color
  vision.