Myers

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Myers PSYCHOLOGY (6th Ed)

• Chapter 5
• Sensation
• James A. McCubbin, PhD
• Clemson University
• Worth Publishers

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Sensation

• Sensation
• a process by which our sensory receptors and
  nervous system receive and represent stimulus
  energy
• Perception
• a process of organizing and interpreting sensory
  information, enabling us to recognize meaningful
  objects and events

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Sensation

• Bottom-Up Processing
• analysis that begins with the sense receptors and
  works up to the brains integration of sensory
  information
• Top-Down Processing
• information processing guided by higher-level
  mental processes
• as when we construct perceptions drawing on our
  experience and expectations

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Sensation- Basic Principles

• Psychophysics
• study of the relationship between physical
  characteristics of stimuli and our psychological
  experience of them
• Light- brightness
• Sound- volume
• Pressure- weight
• Taste- sweetness

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Sensation- Thresholds

• Absolute Threshold
• minimum stimulation needed to detect a particular
  stimulus
• usually defined as the stimulus needed for
  detection 50 of the time
• Difference Threshold
• minimum difference between two stimuli that a
  subject can detect 50 of the time
• just noticeable difference (JND)
• increases with magnitude

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Sensation- Thresholds

• Signal Detection Theory
• predicts how and when we detect the presence of a
  faint stimulus (signal) amid background
  stimulation (noise)
• assumes that there is no single absolute
  threshold
• detection depends partly on persons
• experience
• expectations
• motivation
• level of fatigue

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Sensation- Thresholds

• When stimuli are detectable less than 50 of the
  time (below ones absolute threshold) they are
  subliminal.

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Sensation- Thresholds

• Webers Law- to perceive a difference between
  two stimuli, they must differ by a constant
  proportion
• light intensity- 8
• weight- 2
• tone frequency- 0.3
• Sensory adaptation- diminished sensitivity with
  constant stimulation

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Vision- Stabilized Images on the Retina
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Vision

• Transduction- conversion of one form of energy
  to another
• Wavelength- the distance from the peak of one
  wave to the peak of the next
• Hue- dimension of color determined by wavelength
  of light
• Intensity- amount of energy in a wave determined
  by amplitude
• brightness
• loudness

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Vision- Spectrum of Electromagnetic Energy
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Vision- Physical Properties of Waves
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Vision

• Pupil- adjustable opening in the center of the
  eye
• Iris- a ring of muscle the forms the colored
  portion of the eye around the pupil and controls
  the size of the pupil opening
• Lens- transparent structure behind pupil that
  changes shape to focus images on the retina

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Vision
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Vision

• Accommodation
• change in shape of lens
• focus near objects
• Retina
• inner surface of eye
• light sensitive
• contains rods and cones
• layers of neurons
• beginning of visual information processing

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Vision

• Acuity- the sharpness of vision
• Nearsightedness
• nearby objects seen more clearly
• lens focuses image of distant objects in front of
  retina
• Farsightedness
• faraway objects seen more clearly
• lens focuses near objects behind retina

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Vision

• Normal Nearsighted Farsighted
  Vision Vision Vision

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Retinas Reaction to Light- Receptors

• Cones
• near center of retina (fovea)
• fine detail and color vision
• daylight or well-lit conditions
• Rods
• peripheral retina
• detect black, white and gray
• twilight or low light

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Retinas Reaction to Light

• Optic nerve- nerve that carries neural impulses
  from the eye to the brain
• Blind Spot- point at which the optic nerve leaves
  the eye, creating a blind spot because there
  are no receptor cells located there
• Fovea- central point in the retina, around which
  the eyes cones cluster

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Vision- Receptors
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Pathways from the Eyes to the Visual Cortex
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Visual Information Processing

• Feature Detectors
• neurons in the visual cortex respond to
  specific features
• shape
• angle
• movement

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How the Brain Perceives
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Illusory Contours
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Visual Information Processing

• Parallel Processing
• simultaneous processing of several dimensions
  through multiple pathways
• color
• motion
• form
• depth

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Visual Information Processing
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Visual Information Processing

• Trichromatic (three color) Theory
• Young and Helmholtz
• three different retinal color receptors
• red
• green
• blue

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Color-Deficient Vision

• People who suffer red-green blindness have
  trouble perceiving the number within the design

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Visual Information Processing

• Opponent-Process Theory- opposing retinal
  processes enable color vision
• ON OFF
• red green
• green red
• blue yellow
• yellow blue
• black white
• white black

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Opponent Process- Afterimage Effect
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Audition

• Audition
• the sense of hearing
• Frequency
• the number of complete wavelengths that pass a
  point in a given time
• Pitch
• a tones highness or lowness
• depends on frequency

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The Intensity of Some Common Sounds
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Audition- The Ear

• Outer Ear
• Auditory Canal
• Eardrum
• Middle Ear
• hammer
• anvil
• stirrup
• Inner Ear
• oval window
• cochlea
• basilar membrane
• hair cells

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Audition

• Place Theory
• the theory that links the pitch we hear with the
  place where the cochleas membrane is stimulated
• Frequency Theory
• 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

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How We Locate Sounds
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Audition

• Conduction Hearing Loss
• hearing loss caused by damage to the mechanical
  system that conducts sound waves to the cochlea
• Nerve Hearing Loss
• hearing loss caused by damage to the cochleas
  receptor cells or to the auditory nerve

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Audition

• Older people tend to hear low frequencies well
  but suffer hearing loss for high frequencies

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Touch

• Skin Sensations
• pressure
• only skin sensation with identifiable receptors
• warmth
• cold
• pain

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Pain

• Gate-Control Theory
• theory that the spinal cord contains a
  neurological gate that blocks pain signals or
  allows them to pass on to the brain
• gate opened by the activity of pain signals
  traveling up small nerve fibers
• gate closed by activity in larger fibers or by
  information coming from the brain

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Taste

• Taste Sensations
• sweet
• sour
• salty
• bitter
• Sensory Interaction
• the principle that one sense may influence
  another
• as when the smell of food influences its taste

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Smell
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Age, Sex and Sense of Smell
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Body Position and Movement

• Kinesthesis
• the system for sensing the position and movement
  of individual body parts
• Vestibular Sense
• the sense of body movement and position
• including the sense of balance