This document discusses chapters from a psychology textbook on sensation and perception. It covers topics like the basic principles of sensation including thresholds and sensory adaptation. It describes the senses of vision, hearing, touch, taste, smell, and kinesthesia. It discusses perceptual organization including principles of form, depth, motion and constancy. It examines perceptual interpretation and how experience shapes perception. It analyzes studies on sensory deprivation and adaptation. In 3 sentences or less, it provides an overview of the key topics and concepts covered in the textbook chapters on sensation and perception.

1. 1
PSYCHOLOGY
(9th Edition)
David Myers
PowerPoint Slides
Aneeq Ahmad
Henderson State University
Worth Publishers, © 2010

2. 2
Sensation and
Perception
Chapter 6

3. 3
Sensation
Sensing the World:
Some Basic Principles
 Thresholds
 Sensory Adaptation
Vision
 The Stimulus Input: Light Energy
 The Eye
 Visual Information Processing
 Color Vision

4. 4
Hearing
 The Stimulus Input: Sound Waves
 The Ear
 Hearing Loss and Deaf Culture
Other Important Senses
 Touch
 Pain
 Taste
 Smell

5. 5
Perceptual Organization
 Form Perception
 Depth Perception
 Motion Perception
 Perceptual Constancy

6. 6
Perceptual Interpretation
 Sensory Deprivation and Restored
Vision
 Perceptual Adaptation
 Perceptual Set
 Perception and the Human Factor

7. 7
Is There Extrasensory Perception?
 Claims of ESP
 Premonitions or Pretensions?
 Putting ESP to Experimental Test

8. 8
Sensation & Perception
How do we construct our representations of the
external world?
To represent the world, we must detect physical
energy (a stimulus) from the environment and
convert it into neural signals. This is a process
called sensation.
When we select, organize, and interpret our
sensations, the process is called perception.

9. 9
Bottom-up Processing
Analysis of the stimulus begins with the sense
receptors and works up to the level of the brain
and mind.
Letter “A” is really a black blotch broken down into
features by the brain that we perceive as an “A.”

10. 10
Top-Down Processing
Information processing guided by higher-level
mental processes as we construct perceptions,
drawing on our experience and expectations.
THE CHT

11. 11
Our sensory and perceptual processes work
together to help us sort out complex images.
Making Sense of Complexity
“The Forest Has Eyes,” Bev Doolittle

12. 12
Sensing the World
Senses are nature’s gift that suit an organism’s
needs.
A frog feeds on flying insects; a male silkworm
moth is sensitive to female sex-attractant odor; and
we as human beings are sensitive to sound
frequencies that represent the range of human
voice.

13. 13
Exploring the Senses
What stimuli cross our threshold for
conscious awareness?

14. 14
Psychophysics
A study of the relationship between physical
characteristics of stimuli and our psychological
experience with them.
Physical World
Psychological
World
Light Brightness
Sound Volume
Pressure Weight
Sugar Sweet

15. 15
Thresholds
Absolute Threshold: Minimum stimulation needed
to detect a particular stimulus 50% of the time.
Proportionof“Yes”Responses
0.000.501.00
0 5 10 15 20 25
Stimulus Intensity (lumens)

16. 16
Subliminal Threshold
Subliminal Threshold:
When stimuli are below
one’s absolute threshold for
conscious awareness.
KurtScholz/Superstock

17. 17
Weber’s Law
Two stimuli must differ by a constant minimum
percentage (rather than a constant amount), to be
perceived as different. Weber fraction: k = δI/I.
Stimulus Constant (k)
Light 8%
Weight 2%
Tone 3%

18. 18
Sensory Adaptation
Diminished sensitivity as a consequence of
constant stimulation.
Put a band aid on your arm and after awhile
you don’t sense it.

19. 19
Now you see, now you don’t

20. 20
Vision

21. 21
Transduction
In sensation, the transformation of stimulus energy
(sights, sounds, smells) into neural impulses.

22. 22
Visible
Spectrum
The Stimulus Input: Light EnergyBothPhotos:ThomasEisner

23. 23
Physical Characteristics of Light
1. Wavelength (hue/color)
2. Intensity (brightness)

24. 24
Wavelength (Hue)
Hue (color) is the
dimension of
color determined
by the
wavelength of the
light.
Wavelength is the
distance from the
peak of one wave
to the peak of the
next.

25. 25
Wavelength (Hue)
Different wavelengths of light result
in different colors.
400 nm 700 nm
Long wavelengthsShort wavelengths
Violet Indigo Blue Green Yellow Orange Red

26. 26
Intensity (Brightness)
Intensity:
Amount of
energy in a
wave
determined by
the amplitude.
It is related to
perceived
brightness.

27. 27
Intensity (Brightness)
Blue color with varying levels of intensity.
As intensity increases or decreases, blue color
looks more “washed out” or “darkened.”

28. 28
The Eye

29. 29
Parts of the eye
1. Cornea: Transparent tissue where light enters
the eye.
2. Iris: Muscle that expands and contracts to
change the size of the opening (pupil) for light.
3. Lens: Focuses the light rays on the retina.
4. Retina: Contains sensory receptors that process
visual information and sends it to the brain.

30. 30
The Lens
Lens: Transparent
structure behind the
pupil that changes shape
to focus images on the
retina.
Accommodation: The
process by which the
eye’s lens changes shape
to help focus near or far
objects on the retina.

31. 31
Retina
Retina: The light-
sensitive inner
surface of the eye,
containing receptor
rods and cones in
addition to layers of
other neurons
(bipolar, ganglion
cells) that process
visual information.

32. 32
Optic Nerve, Blind Spot & Fovea
http://www.bergen.org
Optic nerve: Carries neural impulses from the eye to the
brain. Blind Spot: Point where the optic nerve leaves the
eye because there are no receptor cells located there.
Fovea: Central point in the retina around which the eye’s
cones cluster.

33. 33
Test your Blind Spot
Use your textbook. Close your left eye, and fixate
your right eye on the black dot. Move the page
towards your eye and away from your eye. At
some point the car on the right will disappear due
to a blind spot.

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Photoreceptors
E.R. Lewis, Y.Y. Zeevi, F.S Werblin, 1969

35. 35
Bipolar & Ganglion Cells
Bipolar cells receive messages from
photoreceptors and transmit them to ganglion
cells, which converge to form the optic nerve.

36. 36
Visual Information Processing
Optic nerves connect to the thalamus in the
middle of the brain, and the thalamus connects to
the visual cortex.

37. 37
Feature Detection
Nerve cells in the visual cortex respond to
specific features, such as edges, angles, and
movement.
RossKinnaird/Allsport/GettyImages

38. 38
Shape Detection
Specific combinations of temporal lobe activity
occur as people look at shoes, faces, chairs and
houses.
Ishai,Ungerleider,MartinandHaxby/NIMH

39. 39
Visual Information Processing
Processing of several aspects of the stimulus
simultaneously is called parallel processing. The
brain divides a visual scene into subdivisions such
as color, depth, form, movement, etc.

40. 40
From Sensation to Recognition

41. 41
Color Vision
Trichromatic theory: Young and von Helmholtz
suggested that the eye must contain three receptors
that are sensitive to red, blue and green colors.
Blue Green Red
Medium LowMax
Standard stimulus
Comparison stimulus

42. 42
Color Blindness
Ishihara Test
Genetic disorder in which people are blind to
green or red colors. This supports the
Trichromatic theory.

43. 43
Opponent Colors
Gaze at the middle of the flag for about 30
Seconds. When it disappears, stare at the dot and report
whether or not you see Britain's flag.

44. 44
Hearing

45. 45
Hearing
The Stimulus Input: Sound Waves
Sound waves are compressing and expanding air
molecules.

46. 46
Sound Characteristics
1. Frequency (pitch)
2. Intensity (loudness)

47. 47
The Ear
Dr.FredHossler/VisualsUnlimited

48. 48
The Ear
Outer Ear: Collects and sends sounds to the
eardrum.
Middle Ear: Chamber between eardrum and
cochlea containing three tiny bones (hammer,
anvil, stirrup) that concentrate the vibrations
of the eardrum on the cochlea’s oval window.
Inner Ear: Innermost part of the ear,
containing the cochlea, semicircular canals,
and vestibular sacs.

49. 49
Cochlea
Cochlea: Coiled, bony, fluid-filled tube in the
inner ear that transforms sound vibrations to
auditory signals.

50. 50
Intensity (Loudness)
Intensity
(Loudness):
Amount of energy
in a wave,
determined by the
amplitude, relates
to the perceived
loudness.

51. 51
Loudness of Sound
70dB
120dB
RichardKaylin/Stone/GettyImages

52. 52
Frequency (Pitch)
Frequency (pitch):
The dimension of
frequency
determined by the
wavelength of
sound.
Wavelength: The
distance from the
peak of one wave
to the peak of the
next.

53. 53
Localization of Sounds
Because we have two ears, sounds that reach
one ear faster than the other ear cause us to
localize the sound.

54. 54
Localization of Sound
1. Intensity differences
2. Time differences
Time differences as small as 1/100,000 of a second
can cause us to localize sound. The head acts as a
“shadow” or partial sound barrier.

55. 55
Touch
The sense of touch is a mix of four distinct skin
senses—pressure, warmth, cold, and pain.
BruceAyers/Stone/GettyImages

56. 56
Skin Senses
Only pressure has identifiable receptors. All other
skin sensations are variations of pressure,
warmth, cold and pain.
Burning hot
Pressure Vibration Vibration
Cold, warmth and pain

57. 57
Pain
Pain tells the body that something has gone
wrong. Usually pain results from damage to the
skin and other tissues. A rare disease exists in
which the afflicted person feels no pain.
Ashley Blocker (right) feels neither pain
nor extreme hot or cold. APPhoto/StephenMorton

58. 58
Biopsychosocial Influences

59. 59
Gate-Control Theory
Melzack and Wall (1965, 1983) proposed that our
spinal cord contains neurological “gates” that
either block pain or allow it to be sensed.
GaryComer/PhototakeUSA.com

60. 60
Pain Control
Pain can be controlled by a number of therapies
including, drugs, surgery, acupuncture, exercise,
hypnosis, and even thought distraction.
ToddRichardsandAricVills,U.W.
©HunterHoffman,www.vrpain.com

61. 61
Taste
Traditionally, taste sensations consisted of sweet,
salty, sour, and bitter tastes. Recently, receptors for
a fifth taste have been discovered called “Umami”.
Sweet Sour Salty Bitter Umami
(Fresh
Chicken)

62. 62
Sensory Interaction
When one sense affects another sense, sensory
interaction takes place. So, the taste of strawberry
interacts with its smell and its texture on the
tongue to produce flavor.

63. 63
Smell
Like taste, smell is a chemical sense. Odorants
enter the nasal cavity to stimulate 5 million
receptors to sense smell. Unlike taste, there are
many different forms of smell.

64. 64
Smell and Memories
The brain region for
smell (in red) is closely
connected with the
brain regions involved
with memory (limbic
system). That is why
strong memories are
made through the sense
of smell.

65. 65
Body Position and Movement
The sense of our body parts’ position and
movement is called kinesthesis. The vestibular
sense monitors the head (and body’s) position.
http://www.heyokamagazine.com
Whirling Dervishes Wire Walk
BobDaemmrich/TheImageWorks

66. 66
Perceptual Organization
How do we form meaningful perceptions
from sensory information?
We organize it. Gestalt psychologists
showed that a figure formed a “whole”
different than its surroundings.

67. 67
Organization of the visual field into objects
(figures) that stand out from their surroundings
(ground).
Form Perception
TimeSavingsSuggestion,©2003RogerSheperd.

68. 68
Grouping
After distinguishing the figure from the ground,
our perception needs to organize the figure into
a meaningful form using grouping rules.

69. 69
Grouping & Reality
Although grouping principles usually help us construct
reality, they may occasionally lead us astray.
BothphotosbyWalterWick.ReprintedfromGAMES
Magazine..©1983PCSGamesLimitedPartnership

70. 70
Depth Perception
Visual Cliff
Depth perception enables us to judge distances.
Gibson and Walk (1960) suggested that human
infants (crawling age) have depth perception. Even
newborn animals show depth perception.
Innervisions

71. 71
Binocular Cues
Retinal disparity: Images from the two eyes differ. Try
looking at your two index fingers when pointing them
towards each other half an inch apart and about 5 inches
directly in front of your eyes. You will see a “finger
sausage” as shown in the inset.

72. 72
Monocular Cues
Relative Size: If two objects are similar in size, we
perceive the one that casts a smaller retinal image
to be farther away.

73. 73
Monocular Cues
Interposition: Objects that occlude (block) other
objects tend to be perceived as closer.
ReneMagritte,TheBlankSignature,oiloncanvas,
NationalGalleryofArt,Washington.Collectionof
Mr.andMrs.PaulMellon.PhotobyRichardCarafelli.

74. 74
Monocular Cues
Relative Height: We perceive objects that are higher in our
field of vision to be farther away than those that are lower.
ImagecourtesyofShaunP.Vecera,Ph.D.,
adaptedfromstimulithatapperedinVecreraetal.,2002

75. 75
Monocular Cues
Relative motion: Objects closer to a fixation point
move faster and in opposing direction to those
objects that are farther away from a fixation point,
moving slower and in the same direction.

76. 76
Monocular Cues
Linear Perspective: Parallel lines, such as railroad
tracks, appear to converge in the distance. The
more the lines converge, the greater their
perceived distance.
©TheNewYorkerCollection,2002,JackZiegler
fromcartoonbank.com.Allrightsreserved.

77. 77
Monocular Cues
Light and Shadow: Nearby objects reflect more light into
our eyes than more distant objects. Given two identical
objects, the dimmer one appears to be farther away.
From“PerceivingShapeFromShading”byVilayaur
S.Ramachandran.©1988byScientificAmerican,Inc.
Allrightsreserved.

78. 78
Perceptual Constancy
Perceiving objects as unchanging even as
illumination and retinal images change.

79. 79
Perceiving familiar objects as having consistent
color even when changing illumination filters
the light reflected by the object.
Color Constancy
Color Constancy

80. 80
Size-Distance Relationship
The distant monster (below, left) and the top red
bar (below, right) appear bigger because of
distance cues.
FromShepard,1990
AlanChoisnet/TheImageBank

81. 81
Size-Distance Relationship
Both girls in the room are of similar height.
However, we perceive them to be of different
heights as they stand in the two corners of the
room.
Both photos from S. Schwartzenberg/ The Exploratorium

82. 82
Ames Room
The Ames room is designed to demonstrate the size-
distance illusion.

83. 83
Lightness Constancy
The color and brightness of square A and B are the same.
Courtesy
EdwardAdelson

84. 84
Perceptual Interpretation
Immanuel Kant (1724-1804) maintained that
knowledge comes from our inborn ways of
organizing sensory experiences.
John Locke (1632-1704) argued that we learn to
perceive the world through our experiences.
How important is experience in shaping our
perceptual interpretation?

85. 85
Sensory Deprivation & Restored
Vision
After cataract surgery,
blind adults were able
to regain sight. These
individuals could
differentiate figure and
ground relationships,
yet they had difficulty
distinguishing a circle
and a triangle
(Von Senden, 1932).

86. 86
Facial Recognition
After blind adults
regained sight, they were
able to recognize distinct
features, but were unable
to recognize faces.
Normal observers also
show difficulty in facial
recognition when the
lower half of the pictures
are changed.
CourtesyofRichardLeGrand

87. 87
Kittens raised
without exposure to
horizontal lines later
had difficulty
perceiving horizontal
bars.
Blakemore & Cooper (1970)
Sensory Deprivation

88. 88
Perceptual Adaptation
Visual ability to adjust
to an artificially
displaced visual field,
e.g., prism glasses.
CourtesyofHubertDolezal

89. 89
Perceptual Set
A mental predisposition to perceive one thing
and not another. What you see in the center
picture is influenced by flanking pictures.
FromShepard,1990.

90. 90
(a) Loch ness monster or a tree trunk;
(b) Flying saucers or
clouds?
Perceptual Set
Other examples of perceptual set.
FrankSearle,photoAdams/Corbis-Sygma
DickRuhl

91. 91
Is the “magician cabinet” on the floor or hanging from the
ceiling?
Context Effects
Context can radically alter perception.

92. 92
To an East African, the woman sitting is balancing a metal
box on her head, while the family is sitting under a tree.
Cultural Context
Context instilled by culture also alters
perception.

93. 93
Perception Revisited
Is perception innate or acquired?

94. 94
Is There Extrasensory Perception?
Perception without sensory input is called
extrasensory perception (ESP). A large percentage
of scientists do not believe in ESP.

95. 95
Claims of ESP
1. Telepathy: Mind-to-mind communication. One
person sending thoughts and the other
receiving them.
2. Clairvoyance: Perception of remote events,
such as sensing a friend’s house on fire.
3. Precognition: Perceiving future events, such as
a political leader’s death.
Psychokinesis
The power of “mind over matter” such as
levitating a table/influencing a role of the die.